Science.gov

Sample records for sterol synthesis insights

  1. Sterol Synthesis in Diverse Bacteria

    PubMed Central

    Wei, Jeremy H.; Yin, Xinchi; Welander, Paula V.

    2016-01-01

    Sterols are essential components of eukaryotic cells whose biosynthesis and function has been studied extensively. Sterols are also recognized as the diagenetic precursors of steranes preserved in sedimentary rocks where they can function as geological proxies for eukaryotic organisms and/or aerobic metabolisms and environments. However, production of these lipids is not restricted to the eukaryotic domain as a few bacterial species also synthesize sterols. Phylogenomic studies have identified genes encoding homologs of sterol biosynthesis proteins in the genomes of several additional species, indicating that sterol production may be more widespread in the bacterial domain than previously thought. Although the occurrence of sterol synthesis genes in a genome indicates the potential for sterol production, it provides neither conclusive evidence of sterol synthesis nor information about the composition and abundance of basic and modified sterols that are actually being produced. Here, we coupled bioinformatics with lipid analyses to investigate the scope of bacterial sterol production. We identified oxidosqualene cyclase (Osc), which catalyzes the initial cyclization of oxidosqualene to the basic sterol structure, in 34 bacterial genomes from five phyla (Bacteroidetes, Cyanobacteria, Planctomycetes, Proteobacteria, and Verrucomicrobia) and in 176 metagenomes. Our data indicate that bacterial sterol synthesis likely occurs in diverse organisms and environments and also provides evidence that there are as yet uncultured groups of bacterial sterol producers. Phylogenetic analysis of bacterial and eukaryotic Osc sequences confirmed a complex evolutionary history of sterol synthesis in this domain. Finally, we characterized the lipids produced by Osc-containing bacteria and found that we could generally predict the ability to synthesize sterols. However, predicting the final modified sterol based on our current knowledge of sterol synthesis was difficult. Some bacteria

  2. Insights into the mechanisms of sterol transport between organelles.

    PubMed

    Mesmin, Bruno; Antonny, Bruno; Drin, Guillaume

    2013-09-01

    In cells, the levels of sterol vary greatly among organelles. This uneven distribution depends largely on non-vesicular routes of transfer, which are mediated by soluble carriers called lipid-transfer proteins (LTPs). These proteins have a domain with a hydrophobic cavity that accommodates one sterol molecule. However, a demonstration of their role in sterol transport in cells remains difficult. Numerous LTPs also contain membrane-binding elements, but it is not clear how these LTPs couple their ability to target organelles with lipid transport activity. This issue appears critical, since many sterol transporters are thought to act at contact sites between two membrane-bound compartments. Here, we emphasize that biochemical and structural studies provide precious insights into the mode of action of sterol-binding proteins. Recent studies on START, Osh/ORP and NPC proteins suggest models on how these proteins could transport sterol between organelles and, thereby, influence cellular functions.

  3. Genome profiling of sterol synthesis shows convergent evolution in parasites and guides chemotherapeutic attack.

    PubMed

    Fügi, Matthias A; Gunasekera, Kapila; Ochsenreiter, Torsten; Guan, Xueli; Wenk, Markus R; Mäser, Pascal

    2014-05-01

    Sterols are an essential class of lipids in eukaryotes, where they serve as structural components of membranes and play important roles as signaling molecules. Sterols are also of high pharmacological significance: cholesterol-lowering drugs are blockbusters in human health, and inhibitors of ergosterol biosynthesis are widely used as antifungals. Inhibitors of ergosterol synthesis are also being developed for Chagas's disease, caused by Trypanosoma cruzi. Here we develop an in silico pipeline to globally evaluate sterol metabolism and perform comparative genomics. We generate a library of hidden Markov model-based profiles for 42 sterol biosynthetic enzymes, which allows expressing the genomic makeup of a given species as a numerical vector. Hierarchical clustering of these vectors functionally groups eukaryote proteomes and reveals convergent evolution, in particular metabolic reduction in obligate endoparasites. We experimentally explore sterol metabolism by testing a set of sterol biosynthesis inhibitors against trypanosomatids, Plasmodium falciparum, Giardia, and mammalian cells, and by quantifying the expression levels of sterol biosynthetic genes during the different life stages of T. cruzi and Trypanosoma brucei. The phenotypic data correlate with genomic makeup for simvastatin, which showed activity against trypanosomatids. Other findings, such as the activity of terbinafine against Giardia, are not in agreement with the genotypic profile.

  4. Crystal structures of Ophiostoma piceae sterol esterase: structural insights into activation mechanism and product release.

    PubMed

    Gutiérrez-Fernández, Javier; Vaquero, María Eugenia; Prieto, Alicia; Barriuso, Jorge; Martínez, María Jesús; Hermoso, Juan A

    2014-09-01

    Sterol esterases are able to efficiently hydrolyze both sterol esters and triglycerides and to carry out synthesis reactions in the presence of organic solvents. Their high versatility makes them excellent candidates for biotechnological purposes. Sterol esterase from fungus Ophiostoma piceae (OPE) belongs to the family abH03.01 of the Candida rugosa lipase-like proteins. Crystal structures of OPE were solved in this study for the closed and open conformations. Enzyme activation involves a large displacement of the conserved lid, structural rearrangements of loop α16-α17, and formation of a dimer with a large opening. Three PEG molecules are placed in the active site, mimicking chains of the triglyceride substrate, demonstrating the position of the oxyanion hole and the three pockets that accommodate the sn-1, sn-2 and sn-3 fatty acids chains. One of them is an internal tunnel, connecting the active center with the outer surface of the enzyme 30 Å far from the catalytic Ser220. Based on our structural and biochemical results we propose a mechanism by which a great variety of different substrates can be hydrolyzed in OPE paving the way for the construction of new variants to improve the catalytic properties of these enzymes and their biotechnological applications.

  5. Effect of frequency of dosing of plant sterols on plasma cholesterol levels and synthesis rate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to compare the effects of plant sterols (PS) consumed as a single dose (single) at breakfast or as three doses consumed with breakfast, lunch and dinner (divided) on plasma lipoprotien levels and cholesterol endogenous fractional synthesis rate (FSR). A randomized, placebo-controll...

  6. Current and new insights on phytosterol oxides in plant sterol-enriched food.

    PubMed

    García-Llatas, Guadalupe; Rodríguez-Estrada, María Teresa

    2011-09-01

    Over the past 15 years, plant sterol-enriched foods have faced a great increase in the market, due to the asserted cholesterol-lowering effect of plant sterols. However, owing to their chemical structures, plant sterols can oxidize and produce a wide variety of oxidation products with controversial biological effects. Although oxyphytosterols can derive from dietary sources and endogenous formation, their single contribution should be better defined. The following review provides an overall and critical picture on the current knowledge and future perspectives of plant sterols-enriched food, particularly focused on occurrence of plant sterol oxidation products and their biological effects. The final objective of this overview is to evince the different aspects of plant sterols-enriched food that require further research, for a better understanding of the influence of plant sterols and their oxides on consumers' health.

  7. Scap is required for sterol synthesis and crypt growth in intestinal mucosa[S

    PubMed Central

    McFarlane, Matthew R.; Cantoria, Mary Jo; Linden, Albert G.; January, Brandon A.; Liang, Guosheng; Engelking, Luke J.

    2015-01-01

    SREBP cleavage-activating protein (Scap) is an endoplasmic reticulum membrane protein required for cleavage and activation of sterol regulatory element-binding proteins (SREBPs), which activate the transcription of genes in sterol and fatty acid biosynthesis. Liver-specific loss of Scap is well tolerated; hepatic synthesis of sterols and fatty acids is reduced, but mice are otherwise healthy. To determine whether Scap loss is tolerated in the intestine, we generated a mouse model (Vil-Scap−) in which tamoxifen-inducible Cre-ERT2, a fusion protein of Cre recombinase with a mutated ligand binding domain of the human estrogen receptor, ablates Scap in intestinal mucosa. After 4 days of tamoxifen, Vil-Scap− mice succumb with a severe enteropathy and near-complete collapse of intestinal mucosa. Organoids grown ex vivo from intestinal crypts of Vil-Scap− mice are readily killed when Scap is deleted by 4-hydroxytamoxifen. Death is prevented when culture medium is supplemented with cholesterol and oleate. These data show that, unlike the liver, the intestine requires Scap to sustain tissue integrity by maintaining the high levels of lipid synthesis necessary for proliferation of intestinal crypts. PMID:25896350

  8. Primary hyperlipidemias in children: effect of plant sterol supplementation on plasma lipids and markers of cholesterol synthesis and absorption.

    PubMed

    Guardamagna, O; Abello, F; Baracco, V; Federici, G; Bertucci, P; Mozzi, A; Mannucci, L; Gnasso, A; Cortese, C

    2011-06-01

    Plant sterols lower serum cholesterol concentration. Available data have confirmed the lipid-lowering efficacy in adults, while there is a relative dearth of data in children and almost exclusively restricted to subjects with familial hypercholesterolemia (FH). Aim of the present study was to evaluate the efficacy, tolerability and safety of plant sterol supplementation in children with different forms of primary hyperlipidemias. The effect of plant sterol consumption on plasma lipids was evaluated in 32 children with heterozygous FH, 13 children with Familial Combined Hyperlipidemia (FCH) and 13 children with Undefined Hypercholesterolemia (UH) in a 12-week open-label intervention study using plant sterol-enriched yoghurt. Plasma lipids and apolipoproteins were measured by routine methods. Markers of cholesterol synthesis (lathosterol) and absorption (campesterol and sitosterol) were measured by GC-MS. Tolerability and adherence to recommended regimen was very high. A significant reduction was observed in LDL-cholesterol in the three groups (10.7, 14.2 and 16.0% in FH, FCH and UH, respectively). Lathosterol concentrations were unchanged, reflecting a lack of increased synthesis of cholesterol. Of the two absorption markers, only sitosterol showed a slight but significant increase. Daily consumption of plant sterol dairy products favorably changes lipid profile by reducing LDL-cholesterol. To our knowledge, this is the first report of the use of plant sterols-enriched foods in treating children with primary hyperlipidemia such as FCH and UH, likely to be the most frequent form also in the young age in the western populations.

  9. Action of lovastatin, simvastatin, and pravastatin on sterol synthesis and their antiproliferative effect in cultured myoblasts from human striated muscle.

    PubMed

    van Vliet, A K; Nègre-Aminou, P; van Thiel, G C; Bolhuis, P A; Cohen, L H

    1996-11-08

    Lovastatin, simvastatin, and pravastatin are fairly strong inhibitors of sterol synthesis in human myoblasts in culture. Lovastatin and simvastatin have IC50 values of 19 +/- 6 nM and 4.0 +/- 2.3 nM, respectively. Pravastatin is a weaker inhibitor of sterol synthesis (IC50 value of 110 +/- 38 nM). Through inhibition of mevalonate production, these compounds have a distinct inhibiting effect on cell proliferation. Because proliferation of myoblasts is important in the repair of damaged skeletal muscle, experiments were performed to investigate the effect of lovastatin, simvastatin, and pravastatin on cell proliferation and cell viability. The more potent inhibitors of sterol synthesis, lovastatin, and simvastatin, were able to inhibit the proliferation of these cells during 3 days of incubation with drug concentrations of 1 microM for lovastatin and 0.1 microM or 1 microM for simvastatin. DNA synthesis was decreased by more than 80% in the presence of 1 microM of lovastatin or simvastatin. In contrast, under these conditions, pravastatin had no influence on cell proliferation or DNA synthesis, which is probably related to the lack of inhibition of sterol synthesis by pravastatin on extended incubation. The three 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors did not disturb cell viability because mitochondrial dehydrogenase activity and ATP content remained proportional to the number of cells in the culture at any concentration used.

  10. Structural Insights into Inhibition of Sterol 14[alpha]-Demethylase in the Human Pathogen Trypanosoma cruzi

    SciTech Connect

    Lepesheva, Galina I.; Hargrove, Tatiana Y.; Anderson, Spencer; Kleshchenko, Yuliya; Furtak, Vyacheslav; Wawrzak, Zdzislaw; Villalta, Fernando; Waterman, Michael R.

    2010-09-02

    Trypanosoma cruzi causes Chagas disease (American trypanosomiasis), which threatens the lives of millions of people and remains incurable in its chronic stage. The antifungal drug posaconazole that blocks sterol biosynthesis in the parasite is the only compound entering clinical trials for the chronic form of this infection. Crystal structures of the drug target enzyme, Trypanosoma cruzi sterol 14{alpha}-demethylase (CYP51), complexed with posaconazole, another antifungal agent fluconazole and an experimental inhibitor, (R)-4{prime}-chloro-N-(1-(2,4-dichlorophenyl)-2-(1H-imid-azol-1-yl)ethyl)biphenyl-4-carboxamide (VNF), allow prediction of important chemical features that enhance the drug potencies. Combined with comparative analysis of inhibitor binding parameters, influence on the catalytic activity of the trypanosomal enzyme and its human counterpart, and their cellular effects at different stages of the Trypanosoma cruzi life cycle, the structural data provide a molecular background to CYP51 inhibition and azole resistance and enlighten the path for directed design of new, more potent and selective drugs to develop an efficient treatment for Chagas disease.

  11. Selective inhibition of 14 alpha-desmethyl sterol synthesis in Candida albicans by terconazole, a new triazole antimycotic.

    PubMed

    Isaacson, D M; Tolman, E L; Tobia, A J; Rosenthale, M E; McGuire, J L; Vanden Bossche, H; Janssen, P A

    1988-03-01

    Terconazole, a new broad spectrum antimycotic triazole derivative, has been shown to have potent activity against Candida albicans in vitro and to be effective in animal models of yeast infections. The present study explored a possible mechanism of anticandidal activity of terconazole. The compound inhibited production of 14 alpha-desmethyl sterols (e.g. ergosterol) in C. albicans at concentrations (IC50 = 3-6 x 10(-9) M) lower than those inhibiting the in-vitro growth of the yeast. There was concomitant accumulation of methylated sterols, (e.g. lanosterol), which are considered detrimental to normal yeast cell membrane function. Terconazole stimulated incorporation of 14C-acetate into triglycerides, but had no other effect on C. albicans lipid metabolism. At concentrations greater than or equal to 10(-6)M terconazole inhibited the oxidation of 14C-acetate into 14CO2 in C. albicans although the mechanism for this effect remains unclear. These data indicate that terconazole is a specific inhibitor of yeast C-14 desmethyl sterol production in C. albicans. Furthermore, terconazole reduced cytochrome P-450 levels in yeast microsomes at concentrations 10,000-fold below those at which it showed effects on rabbit liver microsomes. These data indicate a species specificity for the biochemical actions of terconazole. The C-14 alpha-desmethylase system in yeast cell membranes is cytochrome P-450 associated. Thus, terconazole, was a potent inhibitor of C-14 desmethyl sterol synthesis. This effect could contribute to the anticandidal activity of the drug.

  12. New insights on the neuroprotective role of sterols and sex steroids: the seladin-1/DHCR24 paradigm.

    PubMed

    Peri, Alessandro; Danza, Giovanna; Benvenuti, Susanna; Luciani, Paola; Deledda, Cristiana; Rosati, Fabiana; Cellai, Ilaria; Serio, Mario

    2009-07-01

    In 2000 a new gene, i.e. seladin-1 (for selective Alzheimer's disease indicator-1) was identified and found to be down regulated in vulnerable brain regions in Alzheimer's disease. Seladin-1 was considered a novel neuroprotective factor, because of its anti-apoptotic properties. Subsequently, it has been demonstrated that seladin-1 corresponds to the gene that encodes 3-beta-hydroxysterol delta-24-reductase (DHCR24), that catalyzes the synthesis of cholesterol from desmosterol. There is evidence that cholesterol plays a fundamental role in maintaining brain homeostasis. Because of its enzymatic activity, seladin-1/DHCR24 has been considered the human homolog of the plant protein DIMINUTO/DWARF1, that is involved in the synthesis of sterol plant hormones. We have recently demonstrated that seladin-1/DHCR24 is a fundamental mediator of the protective effects of estrogens in the brain. This review describes how this protein interacts with cholesterol and estrogens, thus generating a neuroprotective network, that might open new possibilities in the prevention/treatment of neurodegenerative diseases.

  13. The hypoxic regulator of sterol synthesis Nro1 is a nuclear import adaptor

    PubMed Central

    Yeh, Tzu-Lan; Lee, Chih-Yung S.; Amzel, L. Mario; Espenshade, Peter J.; Bianchet, Mario A.

    2011-01-01

    SUMMARY Fission yeast protein Sre1, the homolog of the mammalian sterol regulatory element binding protein (SREBP), is a hypoxic transcription factor required for sterol homeostasis and low oxygen growth. Nro1 regulates the stability of the N-terminal transcription factor domain of Sre1 (Sre1N) by inhibiting the action of the prolyl 4-hydroxylase-like Ofd1 in an oxygen-dependent manner. The crystal structure of Nro1 determined at 2.2 Å resolution shows an all-α-helical fold that can be divided into two domains: a small N-terminal domain and a larger C-terminal HEAT-repeat domain. Follow-up studies showed that Nro1 defines a new class of nuclear import adaptor that functions both in Ofd1 nuclear localization and in the oxygen-dependent inhibition of Ofd1 to control the hypoxic response. PMID:21481773

  14. The Hypoxic Regulator of Sterol Synthesis Nro1 Is a Nuclear Import Adaptor

    SciTech Connect

    T Yeh; C Lee; L Amzel; P Espenshade; M Bianchet

    2011-12-31

    Fission yeast protein Sre1, the homolog of the mammalian sterol regulatory element-binding protein (SREBP), is a hypoxic transcription factor required for sterol homeostasis and low-oxygen growth. Nro1 regulates the stability of the N-terminal transcription factor domain of Sre1 (Sre1N) by inhibiting the action of the prolyl 4-hydroxylase-like Ofd1 in an oxygen-dependent manner. The crystal structure of Nro1 determined at 2.2 {angstrom} resolution shows an all-{alpha}-helical fold that can be divided into two domains: a small N-terminal domain, and a larger C-terminal HEAT-repeat domain. Follow-up studies showed that Nro1 defines a new class of nuclear import adaptor that functions both in Ofd1 nuclear localization and in the oxygen-dependent inhibition of Ofd1 to control the hypoxic response.

  15. Measurement of hepatic sterol synthesis in the Mongolian gerbil in vivo using (/sup 3/H)water: diurnal variation and effect of type of dietary fat

    SciTech Connect

    Mercer, N.J.; Holub, B.J.

    1981-01-01

    The hepatic synthesis of sterol was measured in the male Mongolian gerbil (Meriones unguiculatus) in vivo following the administration of (/sup 3/H)water by monitoring the incorporation of radioactivity into digitonin-precipitable sterol. A diurnal rhythm in cholesterol synthesis was exhibited under conditions of ad libitum feeding with alternating 12-hour periods of light (0200 to 1400 hr) and dark (1400 to 0200 hr). The zenith was reached between 1500 and 2100 hr and the nadir approximately 10-12 hours later between 0200 and 0400 hr, which provided a zenith/nadir ratio of 9.6 to 1.0. The in vivo rates of hepatic sterol synthesis and plasma cholesterol levels were measured in gerbils fed semi-purified diets containing either 19.5% beef tallow + 0.5% safflower, 20% lard, or 20% safflower oil and widely differing ratios of polyunsaturated: saturated fatty acids. All diets were equalized to contain 0.01% cholesterol and 0.05% plant sterol. After 3 days on the experimental diets, the mean rates of cholesterol synthesis (nmol/g liver per hr) were 41.5, 26.6, and 13.8 for animals fed the diets containing beef tallow, lard, and safflower oil, respectively. After 7 and 14 days, synthetic rates were lowest in the gerbils fed safflower oil as were also the plasma cholesterol levels. These results indicate that the type of dietary lipid can significantly influence the in vivo rate of sterol biosynthesis in gerbil liver. This response may contribute, at least in part, to the observed differences in plasma cholesterol levels.

  16. Hepatic and nonhepatic sterol synthesis and tissue distribution following administration of a liver selective HMG-CoA reductase inhibitor, CI-981: comparison with selected HMG-CoA reductase inhibitors.

    PubMed

    Bocan, T M; Ferguson, E; McNally, W; Uhlendorf, P D; Bak Mueller, S; Dehart, P; Sliskovic, D R; Roth, B D; Krause, B R; Newton, R S

    1992-01-24

    Since cholesterol biosynthesis is an integral part of cellular metabolism, several HMG-CoA reductase inhibitors were systematically analyzed in in vitro, ex vivo and in vivo sterol synthesis assays using [14C]acetate incorporation into digitonin precipitable sterols as a marker of cholesterol synthesis. Tissue distribution of radiolabeled CI-981 and lovastatin was also performed. In vitro, CI-981 and PD134967-15 were equipotent in liver, spleen, testis and adrenal, lovastatin was more potent in extrahepatic tissues than liver and BMY21950, pravastatin and PD135023-15 were more potent in liver than peripheral tissues. In ex vivo assays, all inhibitors except lovastatin preferentially inhibited liver sterol synthesis; however, pravastatin and BMY22089 were strikingly less potent in the liver. CI-981 inhibited sterol synthesis in vivo in the liver, spleen and adrenal while not affecting the testis, kidney, muscle and brain. Lovastatin inhibited sterol synthesis to a greater extent than CI-981 in the spleen, adrenal and kidney while pravastatin and BMY22089 primarily affected liver and kidney. The tissue distribution of radiolabeled CI-981 and lovastatin support the changes observed in tissue sterol synthesis. Thus, we conclude that a spectrum of liver selective HMG-CoA reductase inhibitors exist and that categorizing agents as liver selective is highly dependent upon method of analysis.

  17. Green synthesis of β-sitostanol esters catalyzed by the versatile lipase/sterol esterase from Ophiostoma piceae.

    PubMed

    Molina-Gutiérrez, María; Hakalin, Neumara L S; Rodríguez-Sanchez, Leonor; Prieto, Alicia; Martínez, María Jesús

    2017-04-15

    β-sitostanol esters, used as dietary complement for decreasing cholesterol absorption, have been synthesized at 28°C via direct esterification or transesterification catalyzed by the versatile lipase/sterol esterase from the ascomycete fungus O. piceae. Direct esterification was conducted in biphasic isooctane: water systems containing 10mM β-sitostanol and lauric or oleic acid as acyl donors, reaching 90% esterification in 3h with the recombinant enzyme. The use of molar excesses of the free fatty acids did not improve direct esterification rate, and the enzyme did not convert one of the two fatty acids preferentially when both were simultaneously available. On the other hand, solvent-free transesterification was an extremely efficient mechanism to synthesize β-sitostanyl oleate, yielding virtually full conversion of up to 80mM β-sitostanol in 2h. This process may represent a promising green alternative to the current chemical synthesis of these esters of unquestionable nutraceutical value.

  18. Synthesis of Hydroxylated Sterols in Transgenic Arabidopsis Plants Alters Growth and Steroid Metabolism1[C][W][OA

    PubMed Central

    Beste, Lisa; Nahar, Nurun; Dalman, Kerstin; Fujioka, Shozo; Jonsson, Lisbeth; Dutta, Paresh C.; Sitbon, Folke

    2011-01-01

    To explore mechanisms in plant sterol homeostasis, we have here increased the turnover of sterols in Arabidopsis (Arabidopsis thaliana) and potato (Solanum tuberosum) plants by overexpressing four mouse cDNA encoding cholesterol hydroxylases (CHs), hydroxylating cholesterol at the C-7, C-24, C-25, or C-27 positions. Compared to the wild type, the four types of Arabidopsis transformant showed varying degrees of phenotypic alteration, the strongest one being in CH25 lines, which were dark-green dwarfs resembling brassinosteroid-related mutants. Gas chromatography-mass spectrometry analysis of extracts from wild-type Arabidopsis plants revealed trace levels of α and β forms of 7-hydroxycholesterol, 7-hydroxycampesterol, and 7-hydroxysitosterol. The expected hydroxycholesterol metabolites in CH7-, CH24-, and CH25 transformants were identified and quantified using gas chromatography-mass spectrometry. Additional hydroxysterol forms were also observed, particularly in CH25 plants. In CH24 and CH25 lines, but not in CH7 ones, the presence of hydroxysterols was correlated with a considerable alteration of the sterol profile and an increased sterol methyltransferase activity in microsomes. Moreover, CH25 lines contained clearly reduced levels of brassinosteroids, and displayed an enhanced drought tolerance. Equivalent transformations of potato plants with the CH25 construct increased hydroxysterol levels, but without the concomitant alteration of growth and sterol profiles observed in Arabidopsis. The results suggest that an increased hydroxylation of cholesterol and/or other sterols in Arabidopsis triggers compensatory processes, acting to maintain sterols at adequate levels. PMID:21746809

  19. Sterol Regulation of Metabolism, Homeostasis and Development

    PubMed Central

    Wollam, Joshua; Antebi, Adam

    2014-01-01

    Sterol metabolites are critical signaling molecules that regulate metabolism, development, and homeostasis. Oxysterols, bile acids, and steroids work primarily through cognate sterol-responsive nuclear hormone receptors to control these processes through feed-forward and feedback mechanisms. These signaling pathways are conserved from simple invertebrates to mammals. Indeed, results from various model organisms have yielded fundamental insights into cholesterol and bile acid homeostasis, lipid and glucose metabolism, protective mechanisms, tissue differentiation, development, reproduction, and even aging. Here, we review how sterols act through evolutionarily ancient mechanisms to control these processes. PMID:21495846

  20. Cholesterol homeostasis: How do cells sense sterol excess?

    PubMed

    Howe, Vicky; Sharpe, Laura J; Alexopoulos, Stephanie J; Kunze, Sarah V; Chua, Ngee Kiat; Li, Dianfan; Brown, Andrew J

    2016-09-01

    Cholesterol is vital in mammals, but toxic in excess. Consequently, elaborate molecular mechanisms have evolved to maintain this sterol within narrow limits. How cells sense excess cholesterol is an intriguing area of research. Cells sense cholesterol, and other related sterols such as oxysterols or cholesterol synthesis intermediates, and respond to changing levels through several elegant mechanisms of feedback regulation. Cholesterol sensing involves both direct binding of sterols to the homeostatic machinery located in the endoplasmic reticulum (ER), and indirect effects elicited by sterol-dependent alteration of the physical properties of membranes. Here, we examine the mechanisms employed by cells to maintain cholesterol homeostasis.

  1. Retinoic acid-related orphan receptor α regulates diurnal rhythm and fasting induction of sterol 12α-hydroxylase in bile acid synthesis.

    PubMed

    Pathak, Preeti; Li, Tiangang; Chiang, John Y L

    2013-12-27

    Sterol 12α-hydroxylase (CYP8B1) is required for cholic acid synthesis and plays a critical role in intestinal cholesterol absorption and pathogenesis of cholesterol gallstone, dyslipidemia, and diabetes. In this study we investigated the underlying mechanism of fasting induction and circadian rhythm of CYP8B1 by a cholesterol-activated nuclear receptor and core clock gene retinoic acid-related orphan receptor α (RORα). Fasting stimulated, whereas restricted-feeding reduced expression of CYP8B1 mRNA and protein. However, fasting and feeding had little effect on the diurnal rhythm of RORα mRNA expression, but fasting increased RORα protein levels by cAMP-activated protein kinase A-mediated phosphorylation and stabilization of the protein. Adenovirus-mediated gene transduction of RORα to mice strongly induced CYP8B1 expression, and increased liver cholesterol and 12α-hydroxylated bile acids in the bile acid pool and serum. A reporter assay identified a functional RORα response element in the CYP8B1 promoter. RORα recruited cAMP response element-binding protein-binding protein (CBP) to stimulate histone acetylation on the CYP8B1 gene promoter. In conclusion, RORα is a key regulator of diurnal rhythm and fasting induction of CYP8B1, which regulates bile acid composition and serum and liver cholesterol levels. Antagonizing RORα activity may be a therapeutic strategy for treating inflammatory diseases such as non-alcoholic fatty liver disease and type 2 diabetes.

  2. A review of tobacco BY-2 cells as an excellent system to study the synthesis and function of sterols and other isoprenoids.

    PubMed

    Hemmerlin, Andréa; Gerber, Esther; Feldtrauer, Jean-François; Wentzinger, Laurent; Hartmann, Marie-Andrée; Tritsch, Denis; Hoeffler, Jean-François; Rohmer, Michel; Bach, Thomas J

    2004-08-01

    In plants, two pathways are utilized for the synthesis of isopentenyl diphosphate (IPP), the universal precursor for isoprenoid biosynthesis. In this paper we review findings and observations made primarily with tobacco BY-2 cells (TBY-2), which have proven to be an excellent system in which to study the two biosynthetic pathways. A major advantage of these cells as an experimental system is their ability to readily take up specific inhibitors and stably- and/or radiolabeled precursors. This permits the functional elucidation of the role of isoprenoid end products and intermediates. Because TBY-2 cells undergo rapid cell division and can be synchronized within the cell cycle, they constitute a highly suitable test system for determination of those isoprenoids and intermediates that act as cell cycle inhibitors, thus giving an indication of which branches of the isoprenoid pathway are essential. Through chemical complementation; and use of precursors, intracellular compartmentation can be elucidated, as well as the extent to which the plastidial and cytosolic pathways contribute to the syntheses of specific groups of isoprenoids (e.g., sterols) via exchange of intermediates across membranes. These topics are discussed in the context of the pertinent literature.

  3. Enhancement of sterol synthesis by the monoterpene perillyl alcohol is unaffected by competitive 3-hydroxy-3-methylglutaryl-CoA reductase inhibition.

    PubMed

    Cerda, S R; Wilkinson, J; Branch, S K; Broitman, S A

    1999-06-01

    Monoterpenes such as limonene and perillyl alcohol (PA) are currently under investigation for their chemotherapeutic properties which have been tied to their ability to affect protein isoprenylation. Because PA affects the synthesis of isoprenoids, such as ubiquinone, and cholesterol is the end product of the synthetic pathway from which this isoprenoid pathway branches, we investigated the effects of this compound upon cholesterol metabolism in the colonic adenocarcinoma cell line SW480. PA (1 mM) inhibited incorporation of 14C-mevalonate into 21-26 kDa proteins by 25% in SW480 cells. Cholesterol (CH) biosynthesis was assessed by measuring the incorporation of 14C-acetate and 14C-mevalonate into 27-carbon-sterols. Cells treated with PA (1 mM) exhibited a fourfold increase in the incorporation of 14C-acetate but not 14C-mevalonate into cholesterol. Mevinolin (lovastatin), an inhibitor of 3-hydroxy-3-methylglutaryl-CoA(HMG-CoA) reductase, at 2 microM concentration, inhibited CH synthesis from 14C-acetate by 80%. Surprisingly, concurrent addition of mevinolin and PA did not significantly alter the stimulatory effects of PA. As observed differences in 14C-acetate and 14C-mevalonate precursor labeling could indicate PA affects early pathway events, the effects of this monoterpene on HMG-CoA reductase activity were evaluated. Unexpectedly, 1 mM PA did not stimulate activity of this enzyme. Consistent with its action as a reversibly bound inhibitor, in washed microsomes, 2 microM mevinolin pretreatment increased reductase protein expression causing a 12.7 (+/- 2.4)-fold compensatory HMG-CoA reductase activity increase; concurrent treatment with 1 mM PA attenuated this to a 5.3 (+/- 0.03)-fold increase. Gas chromatographic analysis confirmed CH was the major lipid present in the measured thin-layer chromatography spot. Since 14C-acetate incorporation into free fatty acid and phospholipid pools was not significantly affected by PA treatment, nonspecific changes in whole

  4. Overexpression of SREBP1 (sterol regulatory element binding protein 1) promotes de novo fatty acid synthesis and triacylglycerol accumulation in goat mammary epithelial cells.

    PubMed

    Xu, H F; Luo, J; Zhao, W S; Yang, Y C; Tian, H B; Shi, H B; Bionaz, M

    2016-01-01

    Sterol regulatory element binding protein 1 (SREBP1; gene name SREBF1) is known to be the master regulator of lipid homeostasis in mammals, including milk fat synthesis. The major role of SREBP1 in controlling milk fat synthesis has been demonstrated in bovine mammary epithelial cells. Except for a demonstrated role in controlling the expression of FASN, a regulatory role of SREBP1 on milk fat synthesis is very likely, but has not yet been demonstrated in goat mammary epithelial cells (GMEC). To explore the regulatory function of SREBP1 on de novo fatty acids and triacylglycerol synthesis in GMEC, we overexpressed the mature form of SREBP1 (active NH2-terminal fragment) in GMEC using a recombinant adenovirus vector (Ad-nSREBP1), with Ad-GFP (recombinant adenovirus of green fluorescent protein) as control, and infected the GMEC for 48 h. In infected cells, we assessed the expression of 20 genes related to milk fat synthesis using real time-quantitative PCR, the protein abundance of SREBP1 and FASN by Western blot, the production of triacylglycerol, and the fatty acid profile. Expression of SREBF1 was modest in mammary compared with the other tissues in dairy goats but its expression increased approximately 30-fold from pregnancy to lactation. The overexpression of the mature form of SREBP1 was confirmed by >200-fold higher expression of SREBF1 in Ad-nSREBP1 compared with Ad-GFP. We observed no changes in amount of the precursor form of SREBP1 protein but a >10-fold increase of the mature form of SREBP1 protein with Ad-nSREBP1. Compared with Ad-GFP cells (control), Ad-nSREBP1 cells had a significant increase in expression of genes related to long-chain fatty acid activation (ACSL1), transport (FABP3), desaturation (SCD1), de novo synthesis of fatty acids (ACSS2, ACLY, IDH1, ACACA, FASN, and ELOVL6), and transcriptional factors (NR1H3 and PPARG). We observed a >10-fold increase in expression of INSIG1 but SCAP was downregulated by Ad-nSREBP1. Among genes related to

  5. Sterol Biosynthesis Is Required for Heat Resistance but Not Extracellular Survival in Leishmania

    PubMed Central

    Xu, Wei; Hsu, Fong-Fu; Baykal, Eda; Huang, Juyang; Zhang, Kai

    2014-01-01

    Sterol biosynthesis is a crucial pathway in eukaryotes leading to the production of cholesterol in animals and various C24-alkyl sterols (ergostane-based sterols) in fungi, plants, and trypanosomatid protozoa. Sterols are important membrane components and precursors for the synthesis of powerful bioactive molecules, including steroid hormones in mammals. Their functions in pathogenic protozoa are not well characterized, which limits the development of sterol synthesis inhibitors as drugs. Here we investigated the role of sterol C14α-demethylase (C14DM) in Leishmania parasites. C14DM is a cytochrome P450 enzyme and the primary target of azole drugs. In Leishmania, genetic or chemical inactivation of C14DM led to a complete loss of ergostane-based sterols and accumulation of 14-methylated sterols. Despite the drastic change in lipid composition, C14DM-null mutants (c14dm−) were surprisingly viable and replicative in culture. They did exhibit remarkable defects including increased membrane fluidity, failure to maintain detergent resistant membrane fraction, and hypersensitivity to heat stress. These c14dm− mutants showed severely reduced virulence in mice but were highly resistant to itraconazole and amphotericin B, two drugs targeting sterol synthesis. Our findings suggest that the accumulation of toxic sterol intermediates in c14dm− causes strong membrane perturbation and significant vulnerability to stress. The new knowledge may help improve the efficacy of current drugs against pathogenic protozoa by exploiting the fitness loss associated with drug resistance. PMID:25340392

  6. Comparative analysis of sterol acquisition in the oomycetes Saprolegnia parasitica and Phytophthora infestans.

    PubMed

    Dahlin, Paul; Srivastava, Vaibhav; Ekengren, Sophia; McKee, Lauren S; Bulone, Vincent

    2017-01-01

    The oomycete class includes pathogens of animals and plants which are responsible for some of the most significant global losses in agriculture and aquaculture. There is a need to replace traditional chemical means of controlling oomycete growth with more targeted approaches, and the inhibition of sterol synthesis is one promising area. To better direct these efforts, we have studied sterol acquisition in two model organisms: the sterol-autotrophic Saprolegnia parasitica, and the sterol-heterotrophic Phytophthora infestans. We first present a comprehensive reconstruction of a likely sterol synthesis pathway for S. parasitica, causative agent of the disease saprolegniasis in fish. This pathway shows multiple potential routes of sterol synthesis, and draws on several avenues of new evidence: bioinformatic mining for genes with sterol-related functions, expression analysis of these genes, and analysis of the sterol profiles in mycelium grown in different media. Additionally, we explore the extent to which P. infestans, which causes the late blight in potato, can modify exogenously provided sterols. We consider whether the two very different approaches to sterol acquisition taken by these pathogens represent any specific survival advantages or potential drug targets.

  7. Comparative analysis of sterol acquisition in the oomycetes Saprolegnia parasitica and Phytophthora infestans

    PubMed Central

    Dahlin, Paul; Srivastava, Vaibhav; Ekengren, Sophia; McKee, Lauren S.; Bulone, Vincent

    2017-01-01

    The oomycete class includes pathogens of animals and plants which are responsible for some of the most significant global losses in agriculture and aquaculture. There is a need to replace traditional chemical means of controlling oomycete growth with more targeted approaches, and the inhibition of sterol synthesis is one promising area. To better direct these efforts, we have studied sterol acquisition in two model organisms: the sterol-autotrophic Saprolegnia parasitica, and the sterol-heterotrophic Phytophthora infestans. We first present a comprehensive reconstruction of a likely sterol synthesis pathway for S. parasitica, causative agent of the disease saprolegniasis in fish. This pathway shows multiple potential routes of sterol synthesis, and draws on several avenues of new evidence: bioinformatic mining for genes with sterol-related functions, expression analysis of these genes, and analysis of the sterol profiles in mycelium grown in different media. Additionally, we explore the extent to which P. infestans, which causes the late blight in potato, can modify exogenously provided sterols. We consider whether the two very different approaches to sterol acquisition taken by these pathogens represent any specific survival advantages or potential drug targets. PMID:28152045

  8. Pneumocysterol [(24Z)-ethylidenelanost-8-en-3beta-ol], a rare sterol detected in the opportunistic pathogen Pneumocystis carinii hominis: structural identity and chemical synthesis.

    PubMed

    Kaneshiro, E S; Amit, Z; Swonger, M M; Kreishman, G P; Brooks, E E; Kreishman, M; Jayasimhulu, K; Parish, E J; Sun, H; Kizito, S A; Beach, D H

    1999-01-05

    Pneumocystis carinii pneumonia (PcP) remains among the most prevalent opportunistic infections among AIDS patients. Currently, drugs used clinically for deep mycosis act by binding ergosterol or disrupting its biosynthesis. Although classified as a fungus, P. carinii lacks ergosterol. Instead, the pathogen synthesizes a number of distinct Delta7, 24-alkylsterols, despite the abundance of cholesterol, which it can scavenge from the lung alveolus. Thus, the pathogen-specific sterols appear vital for organism survival and proliferation. In the present study, high concentrations of a C32 sterol were found in human-derived P. carinii hominis. The definitive structural identities of two C-24 alkylated lanosterol compounds, previously not reported for rat-derived P. carinii carinii, were determined by using GLC, MS, and NMR spectroscopy together with the chemical syntheses of authentic standards. The C31 and C32 sterols were identified as euphorbol (24-methylenelanost-8-en-3beta-ol) and pneumocysterol [(24Z)-ethylidenelanost-8-en-3beta-ol], respectively. The identification of these and other 24-alkylsterols in P. carinii hominis suggests that (i) sterol C-24 methyltransferase activities are extraordinarily high in this organism, (ii) 24-alkylsterols are important components of the pathogen's membranes, because the addition of these side groups onto the sterol side chain requires substantial ATP equivalents, and (iii) the inefficacy of azole drugs against P. carinii can be explained by the ability of this organism to form 24-alkysterols before demethylation of the lanosterol nucleus. Because mammals cannot form 24-alkylsterols, their biosyntheses in P. carinii are attractive targets for the development of chemotherapeutic strategies against this opportunistic infection.

  9. The effects of sterol structure upon sterol esterification.

    PubMed

    Lin, Don S; Steiner, Robert D; Merkens, Louise S; Pappu, Anuradha S; Connor, William E

    2010-01-01

    Cholesterol is esterified in mammals by two enzymes: LCAT (lecithin cholesterol acyltransferase) in plasma and ACAT(1) and ACAT(2) (acyl-CoA cholesterol acyltransferases) in the tissues. We hypothesized that the sterol structure may have significant effects on the outcome of esterification by these enzymes. To test this hypothesis, we analyzed sterol esters in plasma and tissues in patients having non-cholesterol sterols (sitosterolemia and Smith-Lemli-Opitz syndrome). The esterification of a given sterol was defined as the sterol ester percentage of total sterols. The esterification of cholesterol in plasma by LCAT was 67% and in tissues by ACAT was 64%. Esterification of nine sterols (cholesterol, cholestanol, campesterol, stigmasterol, sitosterol, campestanol, sitostanol, 7-dehydrocholesterol and 8-dehydrocholesterol) was examined. The relative esterification (cholesterol being 1.0) of these sterols by the plasma LCAT was 1.00, 0.95, 0.89, 0.40, 0.85, 0.82 and 0.80, 0.69 and 0.82, respectively. The esterification by the tissue ACAT was 1.00, 1.29, 0.75, 0.49, 0.45, 1.21 and 0.74, respectively. The predominant fatty acid of the sterol esters was linoleic acid for LCAT and oleic acid for ACAT. We compared the esterification of two sterols differing by only one functional group (a chemical group attached to sterol nucleus) and were able to quantify the effects of individual functional groups on sterol esterification. The saturation of the A ring of cholesterol increased ester formation by ACAT by 29% and decreased the esterification by LCAT by 5.9%. Esterification by ACAT and LCAT was reduced, respectively, by 25 and 11% by the presence of an additional methyl group on the side chain of cholesterol at the C-24 position. This data supports our hypothesis that the structure of the sterol substrate has a significant effect on its esterification by ACAT or LCAT.

  10. Molecular insights into protein synthesis with proline residues.

    PubMed

    Melnikov, Sergey; Mailliot, Justine; Rigger, Lukas; Neuner, Sandro; Shin, Byung-Sik; Yusupova, Gulnara; Dever, Thomas E; Micura, Ronald; Yusupov, Marat

    2016-12-01

    Proline is an amino acid with a unique cyclic structure that facilitates the folding of many proteins, but also impedes the rate of peptide bond formation by the ribosome. As a ribosome substrate, proline reacts markedly slower when compared with other amino acids both as a donor and as an acceptor of the nascent peptide. Furthermore, synthesis of peptides with consecutive proline residues triggers ribosome stalling. Here, we report crystal structures of the eukaryotic ribosome bound to analogs of mono- and diprolyl-tRNAs. These structures provide a high-resolution insight into unique properties of proline as a ribosome substrate. They show that the cyclic structure of proline residue prevents proline positioning in the amino acid binding pocket and affects the nascent peptide chain position in the ribosomal peptide exit tunnel. These observations extend current knowledge of the protein synthesis mechanism. They also revise an old dogma that amino acids bind the ribosomal active site in a uniform way by showing that proline has a binding mode distinct from other amino acids.

  11. Inhibition of human polymorphonuclear leukocyte chemotaxis by oxygenated sterol compounds

    SciTech Connect

    Gordon, L.I.; Bass, J.; Yachnin, S.

    1980-07-01

    When preincubated with certain oxygenated sterol compounds in lipoprotein-depleted serum (20% (vol/vol)), human polymorphonuclear leukocytes show inhibition of chemotaxis toward the synthetic dipeptide N-formylmethionylphenylalinine without alteration of random movement or loss of cell viability. These effects can occur at sterol concentrations as low as 6.25 ..mu..M and after as little as 5 min of preincubation, but they are increased at higher concentrations and longer preincubation times. The inhibition can be almost completely reversed by preincubation in lipoprotein-replete serum (human AB serum, 20% (vol/vol)) and may be partially corrected by addition of free cholesterol (0.125 mM) to the medium. These effects are unlikely to be due to inhibition of cellular sterol synthesis, competition for chemotaxin membrane binding sites, or deactivation of the leukocytes but they may be a consequence of insertion of the sterol molecule into the leukocyte plasma membranes.

  12. Intracellular Sterol Dynamics

    PubMed Central

    Mesmin, Bruno; Maxfield, Frederick R.

    2009-01-01

    We review the cellular mechanisms implicated in cholesterol trafficking and distribution. Recent studies have provided new information about the distribution of sterols within cells, including analysis of its transbilayer distribution. The cholesterol interaction with other lipids and its engagement in various trafficking processes will determine its proper level in a specific membrane; making the cholesterol distribution uneven among the various intracellular organelles. The cholesterol content is important since cholesterol plays an essential role in membranes by controlling their physicochemical properties as well as key cellular events such as signal transduction and protein trafficking. Cholesterol movement between cellular organelles is highly dynamic, and can be achieved by vesicular and non-vesicular processes. Various studies have analyzed the proteins that play a significant role in these processes, giving us new information about the relative importance of these two trafficking pathways in cholesterol transport. Although still poorly characterized in many trafficking routes, several potential sterol transport proteins have been described in detail; as a result, molecular mechanisms for sterol transport among membranes start to be appreciated. PMID:19286471

  13. Paleoproterozoic sterol biosynthesis and the rise of oxygen

    NASA Astrophysics Data System (ADS)

    Gold, David A.; Caron, Abigail; Fournier, Gregory P.; Summons, Roger E.

    2017-03-01

    Natural products preserved in the geological record can function as ‘molecular fossils’, providing insight into organisms and physiologies that existed in the deep past. One important group of molecular fossils is the steroidal hydrocarbons (steranes), which are the diagenetic remains of sterol lipids. Complex sterols with modified side chains are unique to eukaryotes, although simpler sterols can also be synthesized by a few bacteria. Sterol biosynthesis is an oxygen-intensive process; thus, the presence of complex steranes in ancient rocks not only signals the presence of eukaryotes, but also aerobic metabolic processes. In 1999, steranes were reported in 2.7 billion year (Gyr)-old rocks from the Pilbara Craton in Australia, suggesting a long delay between photosynthetic oxygen production and its accumulation in the atmosphere (also known as the Great Oxidation Event) 2.45–2.32 Gyr ago. However, the recent reappraisal and rejection of these steranes as contaminants pushes the oldest reported steranes forward to around 1.64 Gyr ago (ref. 6). Here we use a molecular clock approach to improve constraints on the evolution of sterol biosynthesis. We infer that stem eukaryotes shared functionally modern sterol biosynthesis genes with bacteria via horizontal gene transfer. Comparing multiple molecular clock analyses, we find that the maximum marginal probability for the divergence time of bacterial and eukaryal sterol biosynthesis genes is around 2.31 Gyr ago, concurrent with the most recent geochemical evidence for the Great Oxidation Event. Our results therefore indicate that simple sterol biosynthesis existed well before the diversification of living eukaryotes, substantially predating the oldest detected sterane biomarkers (approximately 1.64 Gyr ago), and furthermore, that the evolutionary history of sterol biosynthesis is tied to the first widespread availability of molecular oxygen in the ocean–atmosphere system.

  14. Caffeine catalyzed synthesis of tetrahydrobenzo[b]pyran derivatives: Synthesis and insight into kinetics and mechanism.

    PubMed

    Habibi-Khorassani, Sayyedmostafa; Shahraki, Mehdi; Pourpanah, Sayedeh Shadfar; Mollashahi, Ebrahim; Keshavarz, Shabnam

    2016-10-06

    In this work, synthesis and the feasibility of utilizing a modern in situ spectroscopic method (UV-vis spectrophotometry) has been demonstrated in order to investigate the reaction kinetics between arylaldehydes, malononitrile and dimedone in a mixture of ethanol and water as solvent in the presence of caffeine as a biodegradable catalyst. Attempts for mechanistic insight into the synthesis of a derivative of 4H-tetrahydrobenzo[b]pyrans included spectral kinetics approaches which revealed specific limiting conditions. The influence of various parameters (temperature, solvent and concentration) on the reaction by means of the pseudo-first order kinetic model was studied. Kinetic parameters were calculated. The initial stage of the presented mechanism is defined as a rate-determining step (k1) and is confirmed based upon the steady state approximation.

  15. Plant sterols: Friend or foe in CNS disorders?

    PubMed

    Vanmierlo, Tim; Bogie, Jeroen F J; Mailleux, Jo; Vanmol, Jasmine; Lütjohann, Dieter; Mulder, Monique; Hendriks, Jerome J A

    2015-04-01

    In mammals, the central nervous system (CNS) is the most cholesterol rich organ by weight. Cholesterol metabolism is tightly regulated in the CNS and all cholesterol available is synthesized in situ. Deficits in cholesterol homeostasis at the level of synthesis, transport, or catabolism result in severe disorders featured by neurological disability. Recent studies indicate that a disturbed cholesterol metabolism is involved in CNS disorders, such as Alzheimer's disease (AD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). In contrast to circulating cholesterol, dietary plant sterols, can cross the blood-brain barrier and accumulate in the membranes of CNS cells. Plant sterols are well-known for their ability to lower circulating cholesterol levels. The finding that they gain access to the CNS has fueled research focusing on the physiological roles of plant sterols in the healthy and diseased CNS. To date, both beneficial and detrimental effects of plant sterols on CNS disorders are defined. In this review, we discuss recent findings regarding the impact of plant sterols on homeostatic and pathogenic processes in the CNS, and elaborate on the therapeutic potential of plant sterols in CNS disorders.

  16. Plant Sterols: Diversity, Biosynthesis, and Physiological Functions.

    PubMed

    Valitova, J N; Sulkarnayeva, A G; Minibayeva, F V

    2016-08-01

    Sterols, which are isoprenoid derivatives, are structural components of biological membranes. Special attention is now being given not only to their structure and function, but also to their regulatory roles in plants. Plant sterols have diverse composition; they exist as free sterols, sterol esters with higher fatty acids, sterol glycosides, and acylsterol glycosides, which are absent in animal cells. This diversity of types of phytosterols determines a wide spectrum of functions they play in plant life. Sterols are precursors of a group of plant hormones, the brassinosteroids, which regulate plant growth and development. Furthermore, sterols participate in transmembrane signal transduction by forming lipid microdomains. The predominant sterols in plants are β-sitosterol, campesterol, and stigmasterol. These sterols differ in the presence of a methyl or an ethyl group in the side chain at the 24th carbon atom and are named methylsterols or ethylsterols, respectively. The balance between 24-methylsterols and 24-ethylsterols is specific for individual plant species. The present review focuses on the key stages of plant sterol biosynthesis that determine the ratios between the different types of sterols, and the crosstalk between the sterol and sphingolipid pathways. The main enzymes involved in plant sterol biosynthesis are 3-hydroxy-3-methylglutaryl-CoA reductase, C24-sterol methyltransferase, and C22-sterol desaturase. These enzymes are responsible for maintaining the optimal balance between sterols. Regulation of the ratios between the different types of sterols and sterols/sphingolipids can be of crucial importance in the responses of plants to stresses.

  17. High confidence proteomic analysis of yeast LDs identifies additional droplet proteins and reveals connections to dolichol synthesis and sterol acetylation[S

    PubMed Central

    Currie, Erin; Guo, Xiuling; Christiano, Romain; Chitraju, Chandramohan; Kory, Nora; Harrison, Kenneth; Haas, Joel; Walther, Tobias C.; Farese, Robert V.

    2014-01-01

    Accurate protein inventories are essential for understanding an organelle’s functions. The lipid droplet (LD) is a ubiquitous intracellular organelle with major functions in lipid storage and metabolism. LDs differ from other organelles because they are bounded by a surface monolayer, presenting unique features for protein targeting to LDs. Many proteins of varied functions have been found in purified LD fractions by proteomics. While these studies have become increasingly sensitive, it is often unclear which of the identified proteins are specific to LDs. Here we used protein correlation profiling to identify 35 proteins that specifically enrich with LD fractions of Saccharomyces cerevisiae. Of these candidates, 30 fluorophore-tagged proteins localize to LDs by microscopy, including six proteins, several with human orthologs linked to diseases, which we newly identify as LD proteins (Cab5, Rer2, Say1, Tsc10, YKL047W, and YPR147C). Two of these proteins, Say1, a sterol deacetylase, and Rer2, a cis-isoprenyl transferase, are enzymes involved in sterol and polyprenol metabolism, respectively, and we show their activities are present in LD fractions. Our results provide a highly specific list of yeast LD proteins and reveal that the vast majority of these proteins are involved in lipid metabolism. PMID:24868093

  18. Sterols and sphingolipids: Dynamic duo or partners in crime?

    PubMed Central

    Gulati, Sonia; Liu, Ying; Munkacsi, Andrew B.; Wilcox, Lisa; Sturley, Stephen L.

    2010-01-01

    One manner in which eukaryotic cells respond to their environments is by optimizing the composition and proportions of sterols and sphingolipids in membranes. The physical association of the planar ring of sterols with the acyl chains of phospholipids, particularly sphingolipids, produces membrane micro-heterogeneity that is exploited to coordinate several crucial pathways. We hypothesize that these lipid molecules play an integrated role in human disease; when one of the partners is mis-regulated, pathology frequently ensues. Sterols and sphingolipid levels are not coordinated by the action of a single master regulator, however the cross talk between their metabolic pathways is considerable. We describe our perspectives on the key components of synthesis, catabolism and transport of these lipid partners with an emphasis on evolutionarily conserved reactions that produce disease states when defective. PMID:20362613

  19. Tracking the sterol biosynthesis pathway of the diatom Phaeodactylum tricornutum.

    PubMed

    Fabris, Michele; Matthijs, Michiel; Carbonelle, Sophie; Moses, Tessa; Pollier, Jacob; Dasseville, Renaat; Baart, Gino J E; Vyverman, Wim; Goossens, Alain

    2014-11-01

    Diatoms are unicellular photosynthetic microalgae that play a major role in global primary production and aquatic biogeochemical cycling. Endosymbiotic events and recurrent gene transfers uniquely shaped the genome of diatoms, which contains features from several domains of life. The biosynthesis pathways of sterols, essential compounds in all eukaryotic cells, and many of the enzymes involved are evolutionarily conserved in eukaryotes. Although well characterized in most eukaryotes, the pathway leading to sterol biosynthesis in diatoms has remained hitherto unidentified. Through the DiatomCyc database we reconstructed the mevalonate and sterol biosynthetic pathways of the model diatom Phaeodactylum tricornutum in silico. We experimentally verified the predicted pathways using enzyme inhibitor, gene silencing and heterologous gene expression approaches. Our analysis revealed a peculiar, chimeric organization of the diatom sterol biosynthesis pathway, which possesses features of both plant and fungal pathways. Strikingly, it lacks a conventional squalene epoxidase and utilizes an extended oxidosqualene cyclase and a multifunctional isopentenyl diphosphate isomerase/squalene synthase enzyme. The reconstruction of the P. tricornutum sterol pathway underscores the metabolic plasticity of diatoms and offers important insights for the engineering of diatoms for sustainable production of biofuels and high-value chemicals.

  20. Sterols as Complex-forming Species

    NASA Astrophysics Data System (ADS)

    Ioffe, D. V.

    1986-02-01

    The formation of complexes of sterols with different compounds determines the biological properties of both sterols and various natural substances such as saponins and polyene antibiotics. Complex formation by sterols with phospholipids, steroid saponins, and polyene antibiotics is determined by the same characteristic features of the structure of the sterol molecule. The principal role in complex formation is played by the hydrophobic reaction of the cyclopentanoperhydrophenanthrene ring. The formation of a hydrogen bond between the hydroxyl group of the sterol and a proton acceptor, which is assumed in most complexes, has been proved only in the complexes of sterols with water and acids. The bibliography contains 122 references.

  1. Sterol biosynthesis in oomycete pathogens

    PubMed Central

    Gaulin, Elodie; Bottin, Arnaud

    2010-01-01

    Oomycetes are a diverse group of filamentous eukaryotic microbes comprising devastating animal and plant pathogens. They share many characteristics with fungi, including polarized hyphal extension and production of spores, but phylogenetics studies have clearly placed oomycetes outside the fungal kingdom, in the kingdom Stramenopila which also includes marine organisms such as diatoms and brown algae. Oomycetes display various specific biochemical features, including sterol metabolism. Sterols are essential isoprenoid compounds involved in membrane function and hormone signaling. Oomycetes belonging to Peronosporales, such as Phytophthora sp., are unable to synthesize their own sterols and must acquire them from their plant or animal hosts. In contrast, a combination of biochemical and molecular approaches allowed us to decipher a nearly complete sterol biosynthetic pathway leading to fucosterol in the legume pathogen Aphanomyces euteiches, an oomycete belonging to Saprolegniales. Importantly, sterol demethylase, a key enzyme from this pathway, is susceptible to chemicals widely used in agriculture and medicine as antifungal drugs, suggesting that similar products could be used against plant and animal diseases caused by Saprolegniales. PMID:20023385

  2. Cholesterol-lowering effect of plant sterols.

    PubMed

    AbuMweis, Suhad S; Jones, Peter J H

    2008-12-01

    Plant sterols are plant components that have a chemical structure similar to cholesterol except for the addition of an extra methyl or ethyl group; however, plant sterol absorption in humans is considerably less than that of cholesterol. In fact, plant sterols reduce cholesterol absorption and thus reduce circulating levels of cholesterol. Earlier studies that have tested the efficacy of plant sterols as cholesterol-lowering agents incorporated plant sterols into fat spreads. Later on, plant sterols were added to other food matrices, including juices, nonfat beverages, milk and yogurt, cheese, meat, croissants and muffins, and cereal and chocolate bars. The beneficial physiologic effects of plant sterols could be further enhanced by combining them with other beneficial substances, such as olive and fish oils, fibers, and soy proteins, or with exercise. The addition of plant sterols to the diet is suggested by health experts as a safe and effective way to reduce the risk of coronary heart disease.

  3. Sterols of the fungi - Distribution and biosynthesis.

    NASA Technical Reports Server (NTRS)

    Weete, J. D.

    1973-01-01

    The importance of sterols in the growth and reproduction in fungi is becoming increasingly apparent. This article concerns the composition and biosynthesis of ergosterol in these organisms. Comparison to plant and animal sterol formation are made.

  4. Sterols of the fungi - Distribution and biosynthesis

    NASA Technical Reports Server (NTRS)

    Weete, J. D.

    1973-01-01

    The importance of sterols in the growth and reproduction in fungi is becoming increasingly apparent. This article concerns the composition and biosynthesis of ergosterol in these organisms. Comparison to plant and animal sterol formation are made.

  5. Recent insights in enzymatic synthesis of fructooligosaccharides from inulin.

    PubMed

    Singh, Ram Sarup; Singh, Rupinder Pal; Kennedy, John F

    2016-04-01

    In the past few years, people are paying more attention to their dietary habits, and functional foods are playing a key role in maintaining the health of man. Prebiotics are considered as a main component of the functional foods which are usually composed of short chains of carbohydrates. Fructooligosaccharides (FOSs) are considered as one of the main group of prebiotics which have recognisable bifidogenic properties. FOSs are obtained either by extraction from various plant materials or by enzymatic synthesis from different substrates. Enzymatically, these can be obtained either from sucrose using fructosyltransferase or from inulin by endoinulinase. Inulin is a potent substrate for the enzymatic production of FOSs. This review article will provide an overview on the inulin as potent substrate, microbial sources of endoinulinases, enzymatic synthesis of FOSs from inulin, commercial status of FOSs, and their future perspectives.

  6. Plant Sterol Diversity in Pollen from Angiosperms.

    PubMed

    Villette, Claire; Berna, Anne; Compagnon, Vincent; Schaller, Hubert

    2015-08-01

    Here we have examined the composition of free sterols and steryl esters of pollen from selected angiosperm species, as a first step towards a comprehensive analysis of sterol biogenesis in the male gametophyte. We detected four major sterol structural groups: cycloartenol derivatives bearing a 9β,19-cyclopropyl group, sterols with a double bond at C-7(8), sterols with a double bond at C-5(6), and stanols. All these groups were unequally distributed among species. However, the distribution of sterols as free sterols or as steryl esters in pollen grains indicated that free sterols were mostly Δ(5)-sterols and that steryl esters were predominantly 9β,19-cyclopropyl sterols. In order to link the sterol composition of a pollen grain at anthesis with the requirement for membrane lipid constituents of the pollen tube, we germinated pollen grains from Nicotiana tabacum, a model plant in reproductive biology. In the presence of radiolabelled mevalonic acid and in a time course series of measurements, we showed that cycloeucalenol was identified as the major neosynthesized sterol. Furthermore, the inhibition of cycloeucalenol neosynthesis by squalestatin was in full agreement with a de novo biogenesis and an apparent truncated pathway in the pollen tube.

  7. Effect of chlorpromazine on lipid metabolism in aortas from cholesterol-fed rabbits and normal rats, in vitro: inhibition of sterol esterification and modification of phospholipid synthesis

    SciTech Connect

    Bell, F.P.

    1983-06-01

    Chlorpromazine (CPZ), a major tranquilizer, was found to be a potent inhibitor of acylCoA:cholesterol acyltransferase (ACAT, EC 2.3.1.26) in isolated arterial microsomes and in intact arterial tissue from the rat and cholesterol-fed rabbit in vitro. In isolated rabbit arterial microsomes, CPZ resulted in a concentration-dependent inhibition of ACAT with 50% inhibition of (1-14C)oleoylCoA incorporation into (14C)cholesteryl esters occurring at 0.1 mM CPZ. CPZ also effectively inhibited the incorporation of (14C)oleate into triglycerides without affecting incorporation into diglycerides. Additionally, CPZ altered the pattern of arterial phospholipids synthesized from (1-14C)oleate. Incorporation into phosphatidylcholine was depressed while incorporation into phosphatidylinositol was increased. Since diglyceride synthesis appeared to be unaffected by CPZ, a redirection of phosphatidic acid into the CDP-diglyceride pathway of glycerolipid synthesis does not adequately account for the effect of CPZ on arterial phospholipid and triglyceride synthesis in these experiments.

  8. Mechanistic insight into sonochemical biodiesel synthesis using heterogeneous base catalyst.

    PubMed

    Choudhury, Hanif A; Chakma, Sankar; Moholkar, Vijayanand S

    2014-01-01

    The beneficial effect of ultrasound on transesterification reaction is well known. Heterogeneous (or solid) catalysts for biodiesel synthesis have merit that they do not contaminate the byproduct of glycerol. In this paper, we have attempted to identify the mechanistic features of ultrasound-enhanced biodiesel synthesis with the base-catalyst of CaO. A statistical design of experiments (Box-Behnken) was used to identify the influence of temperature, alcohol to oil molar ratio and catalyst loading on transesterification yield. The optimum values of these parameters for the highest yield were identified through Response Surface Method (with a quadratic model) and ANOVA. These values are: temperature=62 °C, molar ratio=10:1 and catalyst loading=6 wt.%. The activation energy was determined as 82.3 kJ/mol, which is higher than that for homogeneous catalyzed system (for both acidic and basic catalyst). The experimental results have been analyzed vis-à-vis simulations of cavitation bubble dynamics. Due to 3-phase heterogeneity of the system, the yield was dominated by intrinsic kinetics, and the optimum temperature for the highest yield was close to boiling point of methanol. At this temperature, the influence of cavitation bubbles (in terms of both sonochemical and sonophysical effect) is negligible, and ultrasonic micro-streaming provided necessary convection in the system. The influence of all parameters on the reaction system was found to be strongly inter-dependent.

  9. Dietary plant sterols and cholesterol metabolism.

    PubMed

    Ellegård, Lars H; Andersson, Susan W; Normén, A Lena; Andersson, Henrik A

    2007-01-01

    Plant sterols, naturally occurring in foods of plant origin, reduce cholesterol absorption. Experimental studies show plant sterols to be an important part of the serum-cholesterol lowering effect of certain diets and dietary components. Epidemiological data show that individuals with higher intakes of plant sterols from their habitual diets have lower serum-cholesterol levels. To date, the role of naturally occurring plant sterols for lowering serum cholesterol has probably been underestimated. The consumption of dietary plant sterols should be a part of dietary advice to patients with hypercholesterolemia and the general public for the prevention and management of coronary heart disease.

  10. The counterflow transport of sterols and PI4P.

    PubMed

    Mesmin, Bruno; Antonny, Bruno

    2016-08-01

    Cholesterol levels in intracellular membranes are constantly adjusted to match with specific organelle functions. Cholesterol is kept high in the plasma membrane (PM) because it is essential for its barrier function, while low levels are found in the endoplasmic reticulum (ER) where cholesterol mediates feedback control of its own synthesis by sterol-sensor proteins. The ER→Golgi→PM concentration gradient of cholesterol in mammalian cells, and ergosterol in yeast, appears to be sustained by specific intracellular transport processes, which are mostly mediated by lipid transfer proteins (LTPs). Here we review a recently described function of two LTPs, OSBP and its yeast homolog Osh4p, which consists in creating a sterol gradient between membranes by vectorial transport. OSBP also contributes to the formation of ER/Golgi membrane contact sites, which are important hubs for the transfer of several lipid species. OSBP and Osh4p organize a counterflow transport of lipids whereby sterols are exchanged for the phosphoinositide PI4P, which is used as a fuel to drive sterol transport. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

  11. Scaling up complex interventions: insights from a realist synthesis.

    PubMed

    Willis, Cameron D; Riley, Barbara L; Stockton, Lisa; Abramowicz, Aneta; Zummach, Dana; Wong, Geoff; Robinson, Kerry L; Best, Allan

    2016-12-19

    Preventing chronic diseases, such as cancer, cardiovascular disease and diabetes, requires complex interventions, involving multi-component and multi-level efforts that are tailored to the contexts in which they are delivered. Despite an increasing number of complex interventions in public health, many fail to be 'scaled up'. This study aimed to increase understanding of how and under what conditions complex public health interventions may be scaled up to benefit more people and populations.A realist synthesis was conducted and discussed at an in-person workshop involving practitioners responsible for scaling up activities. Realist approaches view causality through the linkages between changes in contexts (C) that activate mechanisms (M), leading to specific outcomes (O) (CMO configurations). To focus this review, three cases of complex interventions that had been successfully scaled up were included: Vibrant Communities, Youth Build USA and Pathways to Education. A search strategy of published and grey literature related to each case was developed, involving searches of relevant databases and nominations from experts. Data extracted from included documents were classified according to CMO configurations within strategic themes. Findings were compared and contrasted with guidance from diffusion theory, and interpreted with knowledge users to identify practical implications and potential directions for future research.Four core mechanisms were identified, namely awareness, commitment, confidence and trust. These mechanisms were activated within two broad scaling up strategies, those of renewing and regenerating, and documenting success. Within each strategy, specific actions to change contexts included building partnerships, conducting evaluations, engaging political support and adapting funding models. These modified contexts triggered the identified mechanisms, leading to a range of scaling up outcomes, such as commitment of new communities, changes in relevant

  12. Fluorescent Sterols and Cholesteryl Esters as Probes for Intracellular Cholesterol Transport

    PubMed Central

    Solanko, Katarzyna A.; Modzel, Maciej; Solanko, Lukasz M.; Wüstner, Daniel

    2015-01-01

    Cholesterol transport between cellular organelles comprised vesicular trafficking and nonvesicular exchange; these processes are often studied by quantitative fluorescence microscopy. A major challenge for using this approach is producing analogs of cholesterol with suitable brightness and structural and chemical properties comparable with those of cholesterol. This review surveys currently used fluorescent sterols with respect to their behavior in model membranes, their photophysical properties, as well as their transport and metabolism in cells. In the first part, several intrinsically fluorescent sterols, such as dehydroergosterol or cholestatrienol, are discussed. These polyene sterols (P-sterols) contain three conjugated double bonds in the steroid ring system, giving them slight fluorescence in ultraviolet light. We discuss the properties of P-sterols relative to cholesterol, outline their chemical synthesis, and explain how to image them in living cells and organisms. In particular, we show that P-sterol esters inserted into low-density lipoprotein can be tracked in the fibroblasts of Niemann–Pick disease using high-resolution deconvolution microscopy. We also describe fluorophore-tagged cholesterol probes, such as BODIPY-, NBD-, Dansyl-, or Pyrene-tagged cholesterol, and eventual esters of these analogs. Finally, we survey the latest developments in the synthesis and use of alkyne cholesterol analogs to be labeled with fluorophores by click chemistry and discuss the potential of all approaches for future applications. PMID:27330304

  13. The sterols of calcareous sponges (Calcarea, Porifera).

    PubMed

    Hagemann, Andrea; Voigt, Oliver; Wörheide, Gert; Thiel, Volker

    2008-11-01

    Sponges are sessile suspension-feeding organisms whose internal phylogenetic relationships are still the subject of intense debate. Sterols may have the potential to be used as independent markers to test phylogenetic hypotheses. Twenty representative specimens of calcareous sponges (class Calcarea, phylum Porifera) with a broad coverage within both subclasses Calcinea and Calcaronea were analysed for their sterol content. Two major pseudohomologous series were found, accompanied by some additional sterols. The first series encompassing conventional C(27) to C(29)Delta(5,7,22) sterols represented the major sterols, with ergosterol (ergosta-5,7,22-trien-3beta-ol, C(28)Delta(5,7,22)) being most prominent in many species. The second series consisted of unusual C(27) to C(29)Delta(5,7,9(11),22) sterols. Cholesterol occurred sporadically, mostly in trace amounts. The sterol patterns did not resolve intraclass phylogenetic relationships, namely the distinction between the subclasses, Calcinea and Calcaronea. This pointed towards major calcarean lipid traits being established prior to the separation of subclasses. Furthermore, calcarean sterol patterns clearly differ from those found in Hexactinellida, whereas partial overlap occurred with some Demospongiae. Hence, sterols only partly reflect the phylogenetic separation of Calcarea from both of the other poriferan classes that was proposed by recent molecular work and fatty acid analyses.

  14. Analysis of molluscan sterols: Colorimetric methods.

    PubMed

    Swift, M L

    1984-08-01

    The wide variety of sterols normally found in extracts of bivalve molluscs leads to high variability in analytical data obtained with colorimetric (chole)sterol methods. Total sterol levels in oyster (Crassostrea virginica) extracts were determined using the Liebermann-Burchard reagent, an acid-FeCl3 reagent and a cholesterol oxidase procedure. The data from the latter two agreed to within 5.4% and yielded about 30% higher estimates of sterol content than the Liebermann-Burchard test. Gas-liquid chromatographic data also are compared.Several pure sterols, selected because of their presence in oyster sterol fractions or because of their structural similarities to such sterols, were examined using each of the three procedures. Sterols, differing from cholesterol only with regard to the side chain, reacted 80-102% as well as cholesterol with the acid-FeCl3 reagent and cholesterol oxidase. The Liebermann-Burchard reaction was more specific for cholesterol. The colorimetric cholesterol oxidase method is recommended for the estimation of total molluscan sterol content.

  15. ABCA1-dependent sterol release: sterol molecule specificity and potential membrane domain for HDL biogenesis

    PubMed Central

    Yamauchi, Yoshio; Yokoyama, Shinji; Chang, Ta-Yuan

    2016-01-01

    Mammalian cells synthesize various sterol molecules, including the C30 sterol, lanosterol, as cholesterol precursors in the endoplasmic reticulum. The build-up of precursor sterols, including lanosterol, displays cellular toxicity. Precursor sterols are found in plasma HDL. How these structurally different sterols are released from cells is poorly understood. Here, we show that newly synthesized precursor sterols arriving at the plasma membrane (PM) are removed by extracellular apoA-I in a manner dependent on ABCA1, a key macromolecule for HDL biogenesis. Analysis of sterol molecules by GC-MS and tracing the fate of radiolabeled acetate-derived sterols in normal and mutant Niemann-Pick type C cells reveal that ABCA1 prefers newly synthesized sterols, especially lanosterol, as the substrates before they are internalized from the PM. We also show that ABCA1 resides in a cholesterol-rich membrane domain resistant to the mild detergent, Brij 98. Blocking ACAT activity increases the cholesterol contents of this domain. Newly synthesized C29/C30 sterols are transiently enriched within this domain, but rapidly disappear from this domain with a half-life of less than 1 h. Our work shows that substantial amounts of precursor sterols are transported to a certain PM domain and are removed by the ABCA1-dependent pathway. PMID:26497474

  16. Building Synthetic Sterols Computationally – Unlocking the Secrets of Evolution?

    PubMed Central

    Róg, Tomasz; Pöyry, Sanja; Vattulainen, Ilpo

    2015-01-01

    Cholesterol is vital in regulating the physical properties of animal cell membranes. While it remains unclear what renders cholesterol so unique, it is known that other sterols are less capable in modulating membrane properties, and there are membrane proteins whose function is dependent on cholesterol. Practical applications of cholesterol include its use in liposomes in drug delivery and cosmetics, cholesterol-based detergents in membrane protein crystallography, its fluorescent analogs in studies of cholesterol transport in cells and tissues, etc. Clearly, in spite of their difficult synthesis, producing the synthetic analogs of cholesterol is of great commercial and scientific interest. In this article, we discuss how synthetic sterols non-existent in nature can be used to elucidate the roles of cholesterol’s structural elements. To this end, we discuss recent atomistic molecular dynamics simulation studies that have predicted new synthetic sterols with properties comparable to those of cholesterol. We also discuss more recent experimental studies that have vindicated these predictions. The paper highlights the strength of computational simulations in making predictions for synthetic biology, thereby guiding experiments. PMID:26347865

  17. Comparative molecular modelling of biologically active sterols

    NASA Astrophysics Data System (ADS)

    Baran, Mariusz; Mazerski, Jan

    2015-04-01

    Membrane sterols are targets for a clinically important antifungal agent - amphotericin B. The relatively specific antifungal action of the drug is based on a stronger interaction of amphotericin B with fungal ergosterol than with mammalian cholesterol. Conformational space occupied by six sterols has been defined using the molecular dynamics method to establish if the conformational features correspond to the preferential interaction of amphotericin B with ergosterol as compared with cholesterol. The compounds studied were chosen on the basis of structural features characteristic for cholesterol and ergosterol and on available experimental data on the ability to form complexes with the antibiotic. Statistical analysis of the data obtained has been performed. The results show similarity of the conformational spaces occupied by all the sterols tested. This suggests that the conformational differences of sterol molecules are not the major feature responsible for the differential sterol - drug affinity.

  18. New Insight into the Synthesis of Large-Pore Ordered Mesoporous Materials.

    PubMed

    Wei, Jing; Sun, Zhenkun; Luo, Wei; Li, Yuhui; Elzatahry, Ahmed A; Al-Enizi, Abdullah M; Deng, Yonghui; Zhao, Dongyuan

    2017-02-08

    Ordered mesoporous materials (OMMs) have received increasing interest due to their uniform pore size, high surface area, various compositions and wide applications in energy conversion and storage, biomedicine and environmental remediation, etc. The soft templating synthesis using surfactants or amphiphilic block copolymers is the most efficient method to produce OMMs with tailorable pore structure and surface property. However, due to the limited choice of commercially available soft templates, the common OMMs usually show small pore size and amorphous (or semicrystalline) frameworks. Tailor-made amphiphilic block copolymers with controllable molecular weights and compositions have recently emerged as alternative soft templates for synthesis of new OMMs with many unique features including adjustable mesostructures and framework compositions, ultralarge pores, thick pore walls, high thermal stability and crystalline frameworks. In this Perspective, recent progresses and some new insights into the coassembly process about the synthesis of OMMs based on these tailor-made copolymers as templates are summarized, and typical newly developed synthesis methods and strategies are discussed in depth, including solvent evaporation induced aggregation, ligand-assisted coassembly, solvent evaporation induced micelle fusion-aggregation assembly, homopolymer assisted pore expanding and carbon-supported crystallization strategy. Then, the applications of the obtained large-pore OMMs in catalysis, sensor, energy conversion and storage, and biomedicine by loading large-size guest molecules (e.g., protein and RNA), precious metal nanoparticles and quantum dots, are discussed. At last, the outlook on the prospects and challenges of future research about the synthesis of large-pore OMMs by using tailor-made amphiphilic block copolymers are included.

  19. Sterol chemotaxonomy of marine pelagophyte algae.

    PubMed

    Giner, José-Luis; Zhao, Hui; Boyer, Gregory L; Satchwell, Michael F; Andersen, Robert A

    2009-07-01

    Several marine algae of the class Pelagophyceae produce the unusual marine sterol 24-propylidenecholesterol, mainly as the (24E)-isomer. The (24Z)-isomer had previously been considered as a specific biomarker for Aureococcus anophagefferens, the 'brown tide' alga of the Northeast coast of the USA. To test this hypothesis and to generate chemotaxonomic information, the sterol compositions of 42 strains of pelagophyte algae including 17 strains of Aureococcus anophagefferens were determined by GC analysis. A more comprehensive sterol analysis by HPLC and (1)H-NMR was obtained for 17 selected pelagophyte strains. All strains analyzed contained 24-propylidenecholesterol. In all strains belonging to the order Sarcinochrysidales, this sterol was found only as the (E)-isomer, while all strains in the order Pelagomonadales contained the (Z)-isomer, either alone or together with the (E)-isomer. The occurrence of Delta(22) and 24alpha-sterols was limited to the Sarcinochrysidales. The first occurrence of Delta(22)-24-propylcholesterol in an alga, CCMP 1410, was reported. Traces of the rare sterol 26,26-dimethyl-24-methylenecholesterol were detected in Aureococcus anophagefferens, and the (25R)-configuration was proposed, based on biosynthetic considerations. Traces of a novel sterol, 24-propylidenecholesta-5,25-dien-3beta-ol, were detected in several species.

  20. The major cellular sterol regulatory pathway is required for Andes virus infection.

    PubMed

    Petersen, Josiah; Drake, Mary Jane; Bruce, Emily A; Riblett, Amber M; Didigu, Chukwuka A; Wilen, Craig B; Malani, Nirav; Male, Frances; Lee, Fang-Hua; Bushman, Frederic D; Cherry, Sara; Doms, Robert W; Bates, Paul; Briley, Kenneth

    2014-02-01

    The Bunyaviridae comprise a large family of RNA viruses with worldwide distribution and includes the pathogenic New World hantavirus, Andes virus (ANDV). Host factors needed for hantavirus entry remain largely enigmatic and therapeutics are unavailable. To identify cellular requirements for ANDV infection, we performed two parallel genetic screens. Analysis of a large library of insertionally mutagenized human haploid cells and a siRNA genomic screen converged on components (SREBP-2, SCAP, S1P and S2P) of the sterol regulatory pathway as critically important for infection by ANDV. The significance of this pathway was confirmed using functionally deficient cells, TALEN-mediated gene disruption, RNA interference and pharmacologic inhibition. Disruption of sterol regulatory complex function impaired ANDV internalization without affecting virus binding. Pharmacologic manipulation of cholesterol levels demonstrated that ANDV entry is sensitive to changes in cellular cholesterol and raises the possibility that clinically approved regulators of sterol synthesis may prove useful for combating ANDV infection.

  1. Sterols from the Madagascar Sponge Fascaplysinopsis sp

    PubMed Central

    Aknin, Maurice; Gros, Emmanuelle; Vacelet, Jean; Kashman, Yoel; Gauvin-Bialecki, Anne

    2010-01-01

    The sponge Fascaplysinopsis sp. (order Dictyoceratida, Family Thorectidae) from the west coast of Madagascar (Indian Ocean) is a particularly rich source of bioactive nitrogenous macrolides. The previous studies on this organism led to the suggestion that the latter should originate from associated microsymbionts. In order to evaluate the influence of microsymbionts on lipid content, 10 samples of Fascaplysinopsis sp. were investigated for their sterol composition. Contrary to the secondary metabolites, the sterol patterns established were qualitatively and quantitatively stable: 14 sterols with different unsaturated nuclei, Δ5, Δ7 and Δ5,7, were identified; the last ones being the main sterols of the investigated sponges. The chemotaxonomic significance of these results for the order Dictyoceratida is also discussed in the context of the literature. The conjugated diene system in Δ5,7 sterols is known to be unstable and easily photo-oxidized during storage and/or experiments to produce 5α,8α-epidioxy sterols. However, in this study, no 5α,8α-epidioxysterols (or only trace amounts) were observed. Thus, it was supposed that photo-oxidation was avoided thanks to the natural antioxidants detected in Fascaplysinopsis sp. by both the DPPH and β-caroten bleaching assays. PMID:21339959

  2. Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi.

    PubMed Central

    Kerwin, J L; Duddles, N D

    1989-01-01

    Several genera of oomycete fungi which are incapable of de novo sterol synthesis do not require these compounds for vegetative growth. The requirement for an exogenous source of sterols for sexual reproduction by several members of the Pythiaceae has been questioned by reports of apparent induction and maturation of oospores on defined media supplemented with phospholipids in the absence of sterols. A more detailed examination of this phenomenon suggested that trace levels of sterols in the inoculum of some pythiaceous fungi act synergistically with phospholipid medium supplements containing unsaturated fatty acid moieties to induce oosporogenesis. Phospholipid analysis of one species, Pythium ultimum, suggested that only the fatty acid portion of the exogenous phospholipid is taken up by the fungus. Enrichment of the phospholipid fraction of total cell lipid of P. ultimum with unsaturated fatty acids promoted oospore induction, and enhanced levels of unsaturated fatty acids in the neutral lipid fraction increased oospore viability. For some pythiaceous fungi, the levels of sterols required for the maturation of oospores with appropriate phospholipid medium supplementation suggest that these compounds are necessary only for the sparking and critical domain roles previously described in other fungi. PMID:2738023

  3. Non-Cholesterol Sterol Levels Predict Hyperglycemia and Conversion to Type 2 Diabetes in Finnish Men

    PubMed Central

    Cederberg, Henna; Gylling, Helena; Miettinen, Tatu A.; Paananen, Jussi; Vangipurapu, Jagadish; Pihlajamäki, Jussi; Kuulasmaa, Teemu; Stančáková, Alena; Smith, Ulf; Kuusisto, Johanna; Laakso, Markku

    2013-01-01

    We investigated the levels of non-cholesterol sterols as predictors for the development of hyperglycemia (an increase in the glucose area under the curve in an oral glucose tolerance test) and incident type 2 diabetes in a 5-year follow-up study of a population-based cohort of Finnish men (METSIM Study, N = 1,050) having non-cholesterol sterols measured at baseline. Additionally we determined the association of 538,265 single nucleotide polymorphisms (SNP) with non-cholesterol sterol levels in a cross-sectional cohort of non-diabetic offspring of type 2 diabetes (the Kuopio cohort of the EUGENE2 Study, N = 273). We found that in a cross-sectional METSIM Study the levels of sterols indicating cholesterol absorption were reduced as a function of increasing fasting glucose levels, whereas the levels of sterols indicating cholesterol synthesis were increased as a function of increasing 2-hour glucose levels. A cholesterol synthesis marker desmosterol significantly predicted an increase, and two absorption markers (campesterol and avenasterol) a decrease in the risk of hyperglycemia and incident type 2 diabetes in a 5-year follow-up of the METSIM cohort, mainly attributable to insulin sensitivity. A SNP of ABCG8 was associated with fasting plasma glucose levels in a cross-sectional study but did not predict hyperglycemia or incident type 2 diabetes. In conclusion, the levels of some, but not all non-cholesterol sterols are markers of the worsening of hyperglycemia and type 2 diabetes. PMID:23840693

  4. Emergent insights from the synthesis of conceptual frameworks for biological invasions.

    PubMed

    Gurevitch, J; Fox, G A; Wardle, G M; Inderjit; Taub, D

    2011-04-01

    A general understanding of biological invasions will provide insights into fundamental ecological and evolutionary problems and contribute to more efficient and effective prediction, prevention and control of invasions. We review recent papers that have proposed conceptual frameworks for invasion biology. These papers offer important advances and signal a maturation of the field, but a broad synthesis is still lacking. Conceptual frameworks for invasion do not require invocation of unique concepts, but rather should reflect the unifying principles of ecology and evolutionary biology. A conceptual framework should incorporate multicausality, include interactions between causal factors and account for lags between various stages. We emphasize the centrality of demography in invasions, and distinguish between explaining three of the most important characteristics by which we recognize invasions: rapid local population increase, monocultures or community dominance, and range expansion. As a contribution towards developing a conceptual synthesis of invasions based on these criteria, we outline a framework that explicitly incorporates consideration of the fundamental ecological and evolutionary processes involved. The development of a more inclusive and mechanistic conceptual framework for invasion should facilitate quantitative and testable evaluation of causal factors, and can potentially lead to a better understanding of the biology of invasions.

  5. Plant sterols in food: No consensus in guidelines

    SciTech Connect

    Weingärtner, Oliver; Baber, Ronny; Teupser, Daniel

    2014-04-11

    Highlights: • Plant sterols are used as food supplement to reduce serum cholesterol levels. • Reductions in serum cholesterol levels are achieved at the expense of increased plant sterol levels. • The potential atherogenicity of increased serum plant sterol levels is controversially debated. • This dispute is reflected by different guideline recommendations in regard to plant sterols. - Abstract: Plant sterols are supplemented in foods to reduce cardiovascular risk. Randomized controlled trials show 2 g of plant sterols a day reduce serum cholesterol by about 10%. This reduction in serum cholesterol levels is achieved at the expense of increased serum plant sterol levels. Findings in patients with phytosterolemia, in experimental studies and in clinical trials have lead to speculations that plant sterols might be atherogenic. In view of emerging safety issues the role of plant sterols in cardiovascular prevention has become controversial. This review reflects the ongoing controversial scientific debate and points out recent developments in guidelines of national and international societies.

  6. Influenza viral membrane fusion is sensitive to sterol concentration but surprisingly robust to sterol chemical identity

    PubMed Central

    Zawada, Katarzyna E.; Wrona, Dominik; Rawle, Robert J.; Kasson, Peter M.

    2016-01-01

    Influenza virions are enriched in cholesterol relative to the plasma membrane from which they bud. Previous work has shown that fusion between influenza virus and synthetic liposomes is sensitive to the amount of cholesterol in either the virus or the target membrane. Here, we test the chemical properties of cholesterol required to promote influenza fusion by replacing cholesterol with other sterols and assaying viral fusion kinetics. We find that influenza fusion with liposomes is surprisingly robust to sterol chemical identity, showing no significant dependence on sterol identity in target membranes for any of the sterols tested. In the viral membrane, lanosterol slowed fusion somewhat, while polar sterols produced a more pronounced slowing and inhibition of fusion. No other sterols tested showed a significant perturbation in fusion rates, including ones previously shown to alter membrane bending moduli or phase behavior. Although fusion rates depend on viral cholesterol, they thus do not require cholesterol’s ability to support liquid-liquid phase coexistence. Using electron cryo-microscopy, we further find that sterol-dependent changes to hemagglutinin spatial patterning in the viral membrane do not require liquid-liquid phase coexistence. We therefore speculate that local sterol-hemagglutinin interactions in the viral envelope may control the rate-limiting step of fusion. PMID:27431907

  7. Influenza viral membrane fusion is sensitive to sterol concentration but surprisingly robust to sterol chemical identity.

    PubMed

    Zawada, Katarzyna E; Wrona, Dominik; Rawle, Robert J; Kasson, Peter M

    2016-07-19

    Influenza virions are enriched in cholesterol relative to the plasma membrane from which they bud. Previous work has shown that fusion between influenza virus and synthetic liposomes is sensitive to the amount of cholesterol in either the virus or the target membrane. Here, we test the chemical properties of cholesterol required to promote influenza fusion by replacing cholesterol with other sterols and assaying viral fusion kinetics. We find that influenza fusion with liposomes is surprisingly robust to sterol chemical identity, showing no significant dependence on sterol identity in target membranes for any of the sterols tested. In the viral membrane, lanosterol slowed fusion somewhat, while polar sterols produced a more pronounced slowing and inhibition of fusion. No other sterols tested showed a significant perturbation in fusion rates, including ones previously shown to alter membrane bending moduli or phase behavior. Although fusion rates depend on viral cholesterol, they thus do not require cholesterol's ability to support liquid-liquid phase coexistence. Using electron cryo-microscopy, we further find that sterol-dependent changes to hemagglutinin spatial patterning in the viral membrane do not require liquid-liquid phase coexistence. We therefore speculate that local sterol-hemagglutinin interactions in the viral envelope may control the rate-limiting step of fusion.

  8. Involvement of the Phospholipid Sterol Acyltransferase1 in Plant Sterol Homeostasis and Leaf Senescence1[W

    PubMed Central

    Bouvier-Navé, Pierrette; Berna, Anne; Noiriel, Alexandre; Compagnon, Vincent; Carlsson, Anders S.; Banas, Antoni; Stymne, Sten; Schaller, Hubert

    2010-01-01

    Genes encoding sterol ester-forming enzymes were recently identified in the Arabidopsis (Arabidopsis thaliana) genome. One belongs to a family of six members presenting homologies with the mammalian Lecithin Cholesterol Acyltransferases. The other one belongs to the superfamily of Membrane-Bound O-Acyltransferases. The physiological functions of these genes, Phospholipid Sterol Acyltransferase1 (PSAT1) and Acyl-CoA Sterol Acyltransferase1 (ASAT1), respectively, were investigated using Arabidopsis mutants. Sterol ester content decreased in leaves of all mutants and was strongly reduced in seeds from plants carrying a PSAT1-deficient mutation. The amount of sterol esters in flowers was very close to that of the wild type for all lines studied. This indicated further functional redundancy of sterol acylation in Arabidopsis. We performed feeding experiments in which we supplied sterol precursors to psat1-1, psat1-2, and asat1-1 mutants. This triggered the accumulation of sterol esters (stored in cytosolic lipid droplets) in the wild type and the asat1-1 lines but not in the psat1-1 and psat1-2 lines, indicating a major contribution of the PSAT1 in maintaining free sterol homeostasis in plant cell membranes. A clear biological effect associated with the lack of sterol ester formation in the psat1-1 and psat1-2 mutants was an early leaf senescence phenotype. Double mutants lacking PSAT1 and ASAT1 had identical phenotypes to psat1 mutants. The results presented here suggest that PSAT1 plays a role in lipid catabolism as part of the intracellular processes at play in the maintenance of leaf viability during developmental aging. PMID:19923239

  9. Purification, characterization and catalytic properties of human sterol 8-isomerase.

    PubMed Central

    Nes, W David; Zhou, Wenxu; Dennis, Allen L; Li, Haoxia; Jia, Zhonghua; Keith, Richard A; Piser, Timothy M; Furlong, Stephen T

    2002-01-01

    CHO 2, encoding human sterol 8-isomerase (hSI), was introduced into plasmids pYX213 or pET23a. The resulting native protein was overexpressed in erg 2 yeast cells and purified to apparent homogeneity. The enzyme exhibited a K (m) of 50 microM and a turnover number of 0.423 s(-1) for zymosterol, an isoelectric point of 7.70, a native molecular mass of 107000 Da and was tetrameric. The structural features of zymosterol provided optimal substrate acceptability. Biomimetic studies of acid-catalysed isomerization of zymosterol resulted in formation of cholest-8(14)-enol, whereas the enzyme-generated product was a Delta(7)-sterol, suggesting absolute stereochemical control of the reaction by hSI. Using (2)H(2)O and either zymosterol or cholesta-7,24-dienol as substrates, the reversibility of the reaction was confirmed by GC-MS of the deuterated products. The positional specific incorporation of deuterium at C-9alpha was established by a combination of (1)H- and (13)C-NMR analyses of the enzyme-generated cholesta-7,24-dienol. Kinetic analyses indicated the reaction equilibrium ( K (eq)=14; DeltaG(o')=-6.5 kJ/mol) for double-bond isomerization favoured the forward direction, Delta(8) to Delta(7). Treatment of hSI with different high-energy intermediate analogues produced the following dissociation constants ( K (i)): emopamil (2 microM)=tamoxifen (1 microM)=tridemorph (1 microM)<25-azacholesterol (21 microM) sterol formation in cholesterol synthesis. PMID:12133002

  10. Nuclear hormone receptors put immunity on sterols

    PubMed Central

    Santori, Fabio R.

    2015-01-01

    Nuclear hormone receptors (NHRs) are transcription factors regulated by small molecules. The functions of NHRs range from development of primary and secondary lymphoid organs, to regulation of differentiation and function of DCs, macrophages and T cells. The human genome has 48 classic (hormone and vitamin receptors) and non-classic (all others) NHRs; 17 non-classic receptors are orphans, meaning that the endogenous ligand is unknown. Understanding the function of orphan NHRs requires the identification of their natural ligands. The mevalonate pathway, including its sterol and non-sterol intermediates and derivatives, is a source of ligands for many classic and non-classic NHRs. For example, cholesterol biosynthetic intermediates (CBIs) are natural ligands for RORγ/γt. CBIs are universal endogenous metabolites in mammalian cells, and to study NHRs that bind CBIs requires ligand-free reporters system in sterol auxotroph cells. Furthermore, RORγ/γt shows broad specificity to sterol lipids, suggesting that RORγ/γt is either a general sterol sensor or specificity is defined by an abundant endogenous ligand. Unlike other NHRs, which regulate specific metabolic pathways, there is no connection between the genetic programs induced by RORγ/γt and ligand biosynthesis. In this review we summarize the roles of non-classic NHRs and their potential ligands in the immune system. PMID:26222181

  11. Effects of sterols on the development and aging of caenorhabditis elegans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because Caenorhabditis elegans lacks several components of the de novo sterol biosynthesis pathway, it requires sterols as essential nutrients. Supplemented cholesterol undergoes extensive enzymatic modification in C. elegans to form other sterols of unknown function. Because sterol metabolism in ...

  12. Involvement of membrane sterols in hypergravity-induced modifications of growth and cell wall metabolism in plant stems

    NASA Astrophysics Data System (ADS)

    Koizumi, T.; Soga, K.; Wakabayashi, K.; Suzuki, M.; Muranaka, T.; Hoson, T.

    Organisms living on land resist the gravitational force by constructing a tough body Plants have developed gravity resistance responses after having first went ashore more than 500 million years ago The mechanisms of gravity resistance responses have been studied under hypergravity conditions which are easily produced on earth by centrifugation In Arabidopsis hypocotyls hypergravity treatment greatly increased the expression level of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase HMGR which is involved in synthesis of terpenoids such as membrane sterols In the present study we examined the role of membrane sterols in gravity resistance in plants by analyzing sterol levels of stem organs grown under hypergravity conditions and by analyzing responses to hypergravity of the organs whose sterol level was modulated Hypergravity inhibited elongation growth but stimulated lateral expansion of Arabidopsis hypocotyls and azuki bean epicotyls Under hypergravity conditions sterol levels were kept high as compared with 1 g controls during incubation Lovastatin an inhibitor HMGR prevented lateral expansion as the gravity resistance response in azuki bean epicotyls Similar results were obtained in analyses with loss of function mutants of HMGR in Arabidopsis It has been shown that sterols play a role in cellulose biosynthesis probably as the primer In wild type Arabidopsis hypocotyls hypergravity increased the cellulose content but it did not influence the content in HMGR mutants These results suggest that hypergravity increases

  13. Biofuels. Altered sterol composition renders yeast thermotolerant.

    PubMed

    Caspeta, Luis; Chen, Yun; Ghiaci, Payam; Feizi, Amir; Buskov, Steen; Hallström, Björn M; Petranovic, Dina; Nielsen, Jens

    2014-10-03

    Ethanol production for use as a biofuel is mainly achieved through simultaneous saccharification and fermentation by yeast. Operating at ≥40°C would be beneficial in terms of increasing efficiency of the process and reducing costs, but yeast does not grow efficiently at those temperatures. We used adaptive laboratory evolution to select yeast strains with improved growth and ethanol production at ≥40°C. Sequencing of the whole genome, genome-wide gene expression, and metabolic-flux analyses revealed a change in sterol composition, from ergosterol to fecosterol, caused by mutations in the C-5 sterol desaturase gene, and increased expression of genes involved in sterol biosynthesis. Additionally, large chromosome III rearrangements and mutations in genes associated with DNA damage and respiration were found, but contributed less to the thermotolerant phenotype.

  14. Plant Oxidosqualene Metabolism: Cycloartenol Synthase–Dependent Sterol Biosynthesis in Nicotiana benthamiana

    PubMed Central

    Gas-Pascual, Elisabet; Berna, Anne; Bach, Thomas J.; Schaller, Hubert

    2014-01-01

    The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9β,19-cyclolanost-24-en-3β-ol) and not lanosterol (lanosta-8,24-dien-3β-ol), as it was shown in the late sixties. However, plant genome mining over the last years revealed the general presence of lanosterol synthases encoding sequences (LAS1) in the oxidosqualene cyclase repertoire, in addition to cycloartenol synthases (CAS1) and to non-steroidal triterpene synthases that contribute to the metabolic diversity of C30H50O compounds on earth. Furthermore, plant LAS1 proteins have been unambiguously identified by peptidic signatures and by their capacity to complement the yeast lanosterol synthase deficiency. A dual pathway for the synthesis of sterols through lanosterol and cycloartenol was reported in the model Arabidopsis thaliana, though the contribution of a lanosterol pathway to the production of 24-alkyl-Δ5-sterols was quite marginal (Ohyama et al. (2009) PNAS 106, 725). To investigate further the physiological relevance of CAS1 and LAS1 genes in plants, we have silenced their expression in Nicotiana benthamiana. We used virus induced gene silencing (VIGS) based on gene specific sequences from a Nicotiana tabacum CAS1 or derived from the solgenomics initiative (http://solgenomics.net/) to challenge the respective roles of CAS1 and LAS1. In this report, we show a CAS1-specific functional sterol pathway in engineered yeast, and a strict dependence on CAS1 of tobacco sterol biosynthesis. PMID:25343375

  15. Plant oxidosqualene metabolism: cycloartenol synthase-dependent sterol biosynthesis in Nicotiana benthamiana.

    PubMed

    Gas-Pascual, Elisabet; Berna, Anne; Bach, Thomas J; Schaller, Hubert

    2014-01-01

    The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9β,19-cyclolanost-24-en-3β-ol) and not lanosterol (lanosta-8,24-dien-3β-ol), as it was shown in the late sixties. However, plant genome mining over the last years revealed the general presence of lanosterol synthases encoding sequences (LAS1) in the oxidosqualene cyclase repertoire, in addition to cycloartenol synthases (CAS1) and to non-steroidal triterpene synthases that contribute to the metabolic diversity of C30H50O compounds on earth. Furthermore, plant LAS1 proteins have been unambiguously identified by peptidic signatures and by their capacity to complement the yeast lanosterol synthase deficiency. A dual pathway for the synthesis of sterols through lanosterol and cycloartenol was reported in the model Arabidopsis thaliana, though the contribution of a lanosterol pathway to the production of 24-alkyl-Δ(5)-sterols was quite marginal (Ohyama et al. (2009) PNAS 106, 725). To investigate further the physiological relevance of CAS1 and LAS1 genes in plants, we have silenced their expression in Nicotiana benthamiana. We used virus induced gene silencing (VIGS) based on gene specific sequences from a Nicotiana tabacum CAS1 or derived from the solgenomics initiative (http://solgenomics.net/) to challenge the respective roles of CAS1 and LAS1. In this report, we show a CAS1-specific functional sterol pathway in engineered yeast, and a strict dependence on CAS1 of tobacco sterol biosynthesis.

  16. The Sterol Methyltransferases SMT1, SMT2, and SMT3 Influence Arabidopsis Development through Nonbrassinosteroid Products1[W][OA

    PubMed Central

    Carland, Francine; Fujioka, Shozo; Nelson, Timothy

    2010-01-01

    Plant sterols are structural components of cell membranes that provide rigidity, permeability, and regional identity to membranes. Sterols are also the precursors to the brassinosteroid signaling molecules. Evidence is accumulating that specific sterols have roles in pattern formation during development. COTYLEDON VASCULAR PATTERNING1 (CVP1) encodes C-24 STEROL METHYLTRANSFERASE2 (SMT2), one of three SMTs in Arabidopsis (Arabidopsis thaliana). SMT2 and SMT3, which also encodes a C-24 SMT, catalyze the reaction that distinguishes the synthesis of structural sterols from signaling brassinosteroid derivatives and are highly regulated. The deficiency of SMT2 in the cvp1 mutant results in moderate developmental defects, including aberrant cotyledon vein patterning, serrated floral organs, and reduced stature, but plants are viable, suggesting that SMT3 activity can substitute for the loss of SMT2. To test the distinct developmental roles of SMT2 and SMT3, we identified a transcript null smt3 mutant. Although smt3 single mutants appear wild type, cvp1 smt3 double mutants show enhanced defects relative to cvp1 mutants, such as discontinuous cotyledon vein pattern, and produce novel phenotypes, including defective root growth, loss of apical dominance, sterility, and homeotic floral transformations. These phenotypes are correlated with major alterations in the profiles of specific sterols but without significant alterations to brassinosteroid profiles. The alterations to sterol profiles in cvp1 mutants affect auxin response, demonstrated by weak auxin insensitivity, enhanced axr1 auxin resistance, ectopically expressed DR5:β-glucuronidase in developing embryos, and defective response to auxin-inhibited PIN2-green fluorescent protein endocytosis. We discuss the developmental roles of sterols implied by these results. PMID:20421456

  17. Mechanisms and genetic determinants regulating sterol absorption, circulating LDL levels, and sterol elimination: implications for classification and disease risk.

    PubMed

    Calandra, Sebastiano; Tarugi, Patrizia; Speedy, Helen E; Dean, Andrew F; Bertolini, Stefano; Shoulders, Carol C

    2011-11-01

    This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestinal and hepatic-derived lipoprotein remnants (LDLR, APOB, APOE, LDLRAP1, PCSK9, IDOL). The insights gained from integrating the wealth of genetic data with biological processes have important implications for the classification of clinical and presymptomatic diagnoses of traditional LDL dyslipidemias, sitosterolemia, and newly emerging phenotypes, as well as their management through both nutritional and pharmaceutical means.

  18. Mechanisms and genetic determinants regulating sterol absorption, circulating LDL levels, and sterol elimination: implications for classification and disease risk

    PubMed Central

    Calandra, Sebastiano; Tarugi, Patrizia; Speedy, Helen E.; Dean, Andrew F.; Bertolini, Stefano; Shoulders, Carol C.

    2011-01-01

    This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestinal and hepatic-derived lipoprotein remnants (LDLR, APOB, APOE, LDLRAP1, PCSK9, IDOL). The insights gained from integrating the wealth of genetic data with biological processes have important implications for the classification of clinical and presymptomatic diagnoses of traditional LDL dyslipidemias, sitosterolemia, and newly emerging phenotypes, as well as their management through both nutritional and pharmaceutical means. PMID:21862702

  19. Methyl sterol and cyclopropane fatty acid composition of Methylococcus capsulatus grown at low oxygen tensions

    NASA Technical Reports Server (NTRS)

    Jahnke, L. L.; Nichols, P. D.

    1986-01-01

    The sterol and fatty acid concentrations for M. capsulatus grown in fed-batch cultures over a wide range of oxygen tensions (0.1-10.6 percent) and at a constant methane level are evaluated. The analyses reveal that the biomass decreases as oxygen levels are lowered; the sterol concentration increases when the oxygen range is between 0.5-1.1 percent and decreases when the oxygen range is below 0.5 percent; and the amount of monounsaturated C16 decreases and the concentration of cyclopropane fatty acids increases after oxygen is reduced. It is noted that growth and membrane synthesis occur at low oxygen concentrations and that the synthesis of membrane lipids responds to growth conditions.

  20. Insights into RNA synthesis, capping, and proofreading mechanisms of SARS-coronavirus.

    PubMed

    Sevajol, Marion; Subissi, Lorenzo; Decroly, Etienne; Canard, Bruno; Imbert, Isabelle

    2014-12-19

    The successive emergence of highly pathogenic coronaviruses (CoVs) such as the Severe Acute Respiratory Syndrome (SARS-CoV) in 2003 and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in 2012 has stimulated a number of studies on the molecular biology. This research has provided significant new insight into functions and activities of the replication/transcription multi-protein complex. The latter directs both continuous and discontinuous RNA synthesis to replicate and transcribe the large coronavirus genome made of a single-stranded, positive-sense RNA of ∼30 kb. In this review, we summarize our current understanding of SARS-CoV enzymes involved in RNA biochemistry, such as the in vitro characterization of a highly active and processive RNA polymerase complex which can associate with methyltransferase and 3'-5' exoribonuclease activities involved in RNA capping, and RNA proofreading, respectively. The recent discoveries reveal fascinating RNA-synthesizing machinery, highlighting the unique position of coronaviruses in the RNA virus world.

  1. Absence of sterols constrains carbon transfer between cyanobacteria and a freshwater herbivore (Daphnia galeata).

    PubMed Central

    von Elert, Eric; Martin-Creuzburg, Dominik; Le Coz, Jean R

    2003-01-01

    A key process in freshwater plankton food webs is the regulation of the efficiency of energy and material transfer. Cyanobacterial carbon (C) in particular is transferred very inefficiently to herbivorous zooplankton, which leads to a decoupling of primary and secondary production and the accumulation of cyanobacterial biomass, which is associated with reduced recreational quality of water bodies and hazards to human health. A recent correlative field study suggested that the low transfer efficiency of cyanobacterial C is the result of the absence of long-chain polyunsaturated fatty acids (PUFA) in the diet of the zooplankton. By supplementation of single-lipid compounds in controlled growth experiments, we show here that the low C transfer efficiency of coccal and filamentous cyanobacteria to the keystone herbivore Daphnia is caused by the low sterol content in cyanobacteria, which constrains cholesterol synthesis and thereby growth and reproduction of the herbivore. Estimations of sterol requirement in Daphnia suggest that, when cyanobacteria comprise more than 80% of the grazed phytoplankton, growth of the herbivore may be limited by sterols and Daphnia may subsequently fail to control phytoplankton biomass. Dietary sterols therefore may play a key role in freshwater food webs and in the control of water quality in lakes dominated by cyanobacteria. PMID:12816661

  2. Algal sterols are as effective as β-sitosterol in reducing plasma cholesterol concentration.

    PubMed

    Chen, Jingnan; Jiao, Rui; Jiang, Yue; Bi, Yanlan; Chen, Zhen-Yu

    2014-01-22

    The present study examined the cholesterol-lowering activity of sterol extract (SE) derived from alga Schizochytrium sp. and its interaction with gene expression of transporters, receptors, and enzymes involved in cholesterol absorption and metabolism. GC-MS analyses found that SE was a mixture of various sterols including lathosterol, ergosterol, stigmasterol, 24-ethylcholesta-5,7,22-trienol, stigmasta-7,24(24(1))-dien-3β-ol, and cholesterol. Results showed that SE at doses of 0.06 and 0.30 g/kg diet were able to decrease plasma cholesterol concentration by 19.5 and 34%, respectively, compared with the control, in hamsters maintained on a 0.1% high-cholesterol diet. SE at a dose of 0.30 g/kg diet was as effective as β-sitosterol in reducing plasma total cholesterol (TC). SE-induced reduction in plasma TC was accompanied by down-regulation of intestinal acyl-CoA:cholesterol acyltransferase 2 (ACAT2) and hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and up-regulation of hepatic low-density lipoprotein (LDL) receptor. Addition of SE to the diet increased the excretion of total fecal sterols. It was concluded that SE possessed the same cholesterol-lowering activity as β-sitosterol and the underlying mechanisms were mediated by increasing sterol excretion and decreasing cholesterol absorption and synthesis.

  3. Synthesis of arborane triterpenols by a bacterial oxidosqualene cyclase

    NASA Astrophysics Data System (ADS)

    Banta, Amy B.; Wei, Jeremy H.; Gill, Clare C. C.; Giner, José-Luis; Welander, Paula V.

    2017-01-01

    Cyclic triterpenoids are a broad class of polycyclic lipids produced by bacteria and eukaryotes. They are biologically relevant for their roles in cellular physiology, including membrane structure and function, and biochemically relevant for their exquisite enzymatic cyclization mechanism. Cyclic triterpenoids are also geobiologically significant as they are readily preserved in sediments and are used as biomarkers for ancient life throughout Earth's history. Isoarborinol is one such triterpenoid whose only known biological sources are certain angiosperms and whose diagenetic derivatives (arboranes) are often used as indicators of terrestrial input into aquatic environments. However, the occurrence of arborane biomarkers in Permian and Triassic sediments, which predates the accepted origin of angiosperms, suggests that microbial sources of these lipids may also exist. In this study, we identify two isoarborinol-like lipids, eudoraenol and adriaticol, produced by the aerobic marine heterotrophic bacterium Eudoraea adriatica. Phylogenetic analysis demonstrates that the E. adriatica eudoraenol synthase is an oxidosqualene cyclase homologous to bacterial lanosterol synthases and distinct from plant triterpenoid synthases. Using an Escherichia coli heterologous sterol expression system, we demonstrate that substitution of four amino acid residues in a bacterial lanosterol synthase enabled synthesis of pentacyclic arborinols in addition to tetracyclic sterols. This variant provides valuable mechanistic insight into triterpenoid synthesis and reveals diagnostic amino acid residues to differentiate between sterol and arborinol synthases in genomic and metagenomic datasets. Our data suggest that there may be additional bacterial arborinol producers in marine and freshwater environments that could expand our understanding of these geologically informative lipids.

  4. Sitosterol-containing lipoproteins trigger free sterol-induced caspase-independent death in ACAT-competent macrophages.

    PubMed

    Bao, Liping; Li, Yankun; Deng, Shi-Xian; Landry, Donald; Tabas, Ira

    2006-11-03

    Sitosterolemia is a disease characterized by very high levels of sitosterol and other plant sterols and premature atherothrombotic vascular disease. One theory holds that plant sterols can directly promote atherosclerosis, but the mechanism is not known. Unesterified, or "free," cholesterol (FC) is a potent inducer of macrophage death, which causes plaque necrosis, a precursor to atherothrombosis. FC-induced macrophage death, however, requires dysfunction of the sterol esterifying enzyme acyl-coenzyme A-cholesterol acyltransferase (ACAT), which likely occurs slowly during lesion progression. In contrast, plant sterols are relatively poorly esterified by ACAT, and so they may cause macrophage death and plaque necrosis in an accelerated manner. In support of this hypothesis, we show here that macrophages incubated with sitosterol-containing lipoproteins accumulate free sterols and undergo death in the absence of an ACAT inhibitor. As with FC loading, sitosterol-induced macrophage death requires sterol trafficking to the endoplasmic reticulum, and sitosterol-enriched endoplasmic reticulum membranes show evidence of membrane protein dysfunction. However, whereas FC induces caspase-dependent apoptosis through activation of the unfolded protein response and JNK, sitosterol-induced death is caspase-independent and involves neither the unfolded protein response nor JNK. Rather, cell death shows signs of necroptosis and autophagy and is suppressed by inhibitors of both processes. These data establish two new concepts. First, a relatively subtle change in sterol structure fundamentally alters the type of death program triggered in macrophages. Understanding the basis of this alteration should provide new insights into the molecular basis of death pathway signaling. Second, sitosterol-induced macrophage death does not require ACAT dysfunction and so may occur in an accelerated fashion. Pending future in vivo studies, this concept may provide at least one mechanism for

  5. C27 to C32 sterols found in Pneumocystis, an opportunistic pathogen of immunocompromised mammals.

    PubMed

    Kaneshiro, E S; Wyder, M A

    2000-03-01

    Pneumocystis carinii is the paradigm of opportunistic infections in immunocompromised mammals. Prior to the acquired immunodeficiency syndrome (AIDS) pandemic and the use of immunosuppressive therapy in organ transplant and cancer patients, P. carinii was regarded as a curiosity, rarely observed clinically. Interest in this organism exploded when it was identified as the agent of P. carinii pneumonia (PcP), the direct cause of death among many AIDS patients. Aggressive prophylaxis has decreased the number of acute PcP cases, but it remains among the most prevalent opportunistic infections found within this patient population. The taxonomic assignment of P. carinii has long been argued; molecular genetics data now demonstrate that it is a fungus. Several antimycotic drugs are targeted against ergosterol or its biosynthesis, but these are not as effective against PcP as they are against other fungal infections. This can now be explained in part by the identification of the sterols of P. carinii. The organism lacks ergosterol but contains distinct C28 and C29 delta7 24-alkylsterols. Also, 24-methylenelanost-8-en-3beta-ol (C31) and pneumocysterol, (24Z)-ethylidenelanost-8-en-3beta-ol (C32) were recently identified in organisms infecting humans. Together, the delta7 24-alkylsterols and pneumocysterol are regarded as signature lipids of the pathogen that can be useful for the diagnosis of PcP, since no other lung pathogen is known to contain them. Cholesterol (C27), the dominant sterol component in P. carinii, is probably totally scavenged from the host. De novo synthesis of sterols has been demonstrated by the presence of lovastatin-sensitive 3-hydroxy-3-methylglutaryl-CoA reductase activity, the incorporation of radiolabeled mevalonate and squalene into P. carinii sterols, and the reduction in cellular ATP in cells treated with inhibitors of enzymes in sterol biosynthesis.

  6. Control of crystallite and particle size in the synthesis of layered double hydroxides: Macromolecular insights and a complementary modeling tool.

    PubMed

    Galvão, Tiago L P; Neves, Cristina S; Caetano, Ana P F; Maia, Frederico; Mata, Diogo; Malheiro, Eliana; Ferreira, Maria J; Bastos, Alexandre C; Salak, Andrei N; Gomes, José R B; Tedim, João; Ferreira, Mário G S

    2016-04-15

    Zinc-aluminum layered double hydroxides with nitrate intercalated (Zn(n)Al-NO3, n=Zn/Al) is an intermediate material for the intercalation of different functional molecules used in a wide range of industrial applications. The synthesis of Zn(2)Al-NO3 was investigated considering the time and temperature of hydrothermal treatment. By examining the crystallite size in two different directions, hydrodynamic particle size, morphology, crystal structure and chemical species in solution, it was possible to understand the crystallization and dissolution processes involved in the mechanisms of crystallite and particle growth. In addition, hydrogeochemical modeling rendered insights on the speciation of different metal cations in solution. Therefore, this tool can be a promising solution to model and optimize the synthesis of layered double hydroxide-based materials for industrial applications.

  7. Treatment of Smith-Lemli-Opitz Syndrome and Other Sterol Disorders

    PubMed Central

    Svoboda, Melissa D.; Christie, Jill M.; Eroglu, Yasemen; Freeman, Kurt A.; Steiner, Robert D.

    2013-01-01

    Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive genetic condition with a broad phenotype that results from deficiency of the final enzyme of the cholesterol synthesis pathway. This defect causes low or low-normal plasma cholesterol levels and increased 7- and 8-dehydrocholesterol (DHC) levels. Many therapies for SLOS and other disorders of sterol metabolism have been proposed, and a few of them have been undertaken in selected patients, but robust prospective clinical trials with validated outcome measures are lacking. We review the current literature and expert opinion on treatments for SLOS and other selected sterol disorders, including dietary cholesterol therapy, statin treatment, bile acid supplementation, medical therapies and surgical interventions, as well as directions for future therapies and treatment research. PMID:23042642

  8. Distribution of sterols in the fungi. I - Fungal spores

    NASA Technical Reports Server (NTRS)

    Weete, J. D.; Laseter, J. L.

    1974-01-01

    Mass spectrometry was used to examine freely extractable sterols from spores of several species of fungi. Ergosterol was the most common sterol produced by any individual species, but it was completely absent from two species belonging to apparently distantly related groups of fungi: the aquatic Phycomycetes and the rust fungi. This fact could have taxonomic or phylogenetic implications. The use of glass capillary columns in the resolution of the sterols is shown to eliminate some of the difficulty inherent in this process.

  9. [Plant sterols, cholesterol precursors and oxysterols: small amounts, big effects].

    PubMed

    Olkkonen, Vesa M; Gylling, Helena; Ikonen, Elina

    2015-01-01

    Noncholesterol sterols are present in the body in very low concentrations compared with cholesterol. Minor structural changes in sterols give them completely individual biological activities. Steroid hormones are the best known example of this. The knowledge of other relatives of cholesterol, particularly plant sterols, cholesterol precursors and oxysterols, their properties, physiological effects, significance in disease processes and diagnostic applications has recently undergone a rapid increase.

  10. Serum lipids, plant sterols, and cholesterol kinetic responses to plant sterol supplementation in phytosterolemia heterozygotes and control individuals123

    PubMed Central

    Myrie, Semone B; Mymin, David; Triggs-Raine, Barbara; Jones, Peter JH

    2012-01-01

    Background: Plant sterol (PS) supplementation is increasingly accepted as a dietary strategy to lower plasma cholesterol concentrations. However, information is scarce about the effect of increased PS intake in potentially vulnerable groups, such as phytosterolemia heterozygotes (HET). Objective: This study assessed the responsiveness of circulating PS and lipid concentrations and cholesterol kinetics (absorption and synthesis) to daily PS supplementation in HET (ABCG8 S107X mutation) compared with a healthy control cohort. Design: A double-blind, randomized, crossover, placebo-controlled study was conducted in 10 HET and 15 control subjects. The participants had a mean (±SEM) age of 34 ± 2 y and a BMI (in kg/m2) of 29.9 ± 1.1 and consumed ∼1.6 g PS or placebo capsules daily with supper for 4 wk. Cholesterol absorption and synthesis were assessed by using [13C]cholesterol and deuterium oxide, respectively. Results: Plasma LDL-cholesterol concentrations decreased (P = 0.006) in both groups after PS supplementation (HET: 2.73 ± 0.19 mmol/L; control: 3.11± 0.19 mmol/L) compared with placebo (HET: 3.12 ± 0.20 mmol/L; control: 3.50 ± 0.21 mmol/L), whereas PS concentrations (campesterol+β-sitosterol) increased (P = 0.03) in both groups after PS supplementation (HET: 39.72 ± 6.05 μmol/L; control: 24.03 ± 1.65 μmol/L) compared with placebo (HET: 27.32 ± 3.80 μmol/L; control: 21.12 ± 2.05 μmol/L). Cholesterol absorption efficiency decreased (P = 0.010) by ∼22% and ∼17% and synthesis rates increased (P = 0.040) by ∼20% and ∼24% in the HET and control groups, respectively, in response to PS consumption compared with placebo. Conclusion: These data suggest that heterozygosity for the ABCG8 S107X mutation does not influence the action of dietary PS on circulating cholesterol concentrations but may affect sterol absorption. This trial was registered at clinicaltrials.gov as NCT01102647. PMID:22378727

  11. Δ24-Sterol Methyltransferase Plays an Important Role in the Growth and Development of Sporothrix schenckii and Sporothrix brasiliensis

    PubMed Central

    Borba-Santos, Luana P.; Visbal, Gonzalo; Gagini, Thalita; Rodrigues, Anderson M.; de Camargo, Zoilo P.; Lopes-Bezerra, Leila M.; Ishida, Kelly; de Souza, Wanderley; Rozental, Sonia

    2016-01-01

    Inhibition of Δ24-sterol methyltransferase (24-SMT) in Sporothrix schenckii sensu stricto and Sporothrix brasiliensis was investigated in vitro. The effects on fungal growth and sterol composition of the 24-SMT inhibitor 22-hydrazone-imidazolin-2-yl-chol-5-ene-3β-ol (H3) were compared to those of itraconazole. MIC and MFC analysis showed that H3 was more effective than itraconazole against both species in both their filamentous and yeast forms. H3 showed fungistatic activity in a time-kill assay, with inhibitory activity stronger than that of itraconazole. GC analysis of cell sterol composition showed that sterols present in control cells (ergosterol and precursors) were completely replaced by 14α-methylated sterols after H3 exposure. Itraconazole only partially inhibited ergosterol synthesis but completely arrested synthesis of other sterols found in control cells, promoting accumulation of nine 14α-methyl sterols. Based on these results, we propose a schematic model of sterol biosynthesis pathways in S. schenckii and S. brasiliensis. Effects on cell morphology due to 24-SMT inhibition by H3 as analyzed by SEM and TEM included irregular cell shape, reduced cytoplasmic electron-density, and reduced thickness of the microfibrillar cell wall layer. Moreover, 24-SMT inhibition by H3 promoted mitochondrial disturbance, as demonstrated by alterations in MitoTracker® Red CMXRos fluorescence intensity evaluated by flow cytometry. When used in conjunction with itraconazole, H3 enhanced the effectiveness of itraconazole against all tested strains, reducing at least half (or more) the MIC values of itraconazole. In addition, cytotoxicity assays revealed that H3 was more selective toward these fungi than was itraconazole. Thus, 24-SMT inhibition by H3 was an effective antifungal strategy against S. schenckii and S. brasiliensis. Inhibition of the methylation reaction catalyzed by 24-SMT has a strong antiproliferative effect via disruption of ergosterol homeostasis

  12. Δ(24)-Sterol Methyltransferase Plays an Important Role in the Growth and Development of Sporothrix schenckii and Sporothrix brasiliensis.

    PubMed

    Borba-Santos, Luana P; Visbal, Gonzalo; Gagini, Thalita; Rodrigues, Anderson M; de Camargo, Zoilo P; Lopes-Bezerra, Leila M; Ishida, Kelly; de Souza, Wanderley; Rozental, Sonia

    2016-01-01

    Inhibition of Δ(24)-sterol methyltransferase (24-SMT) in Sporothrix schenckii sensu stricto and Sporothrix brasiliensis was investigated in vitro. The effects on fungal growth and sterol composition of the 24-SMT inhibitor 22-hydrazone-imidazolin-2-yl-chol-5-ene-3β-ol (H3) were compared to those of itraconazole. MIC and MFC analysis showed that H3 was more effective than itraconazole against both species in both their filamentous and yeast forms. H3 showed fungistatic activity in a time-kill assay, with inhibitory activity stronger than that of itraconazole. GC analysis of cell sterol composition showed that sterols present in control cells (ergosterol and precursors) were completely replaced by 14α-methylated sterols after H3 exposure. Itraconazole only partially inhibited ergosterol synthesis but completely arrested synthesis of other sterols found in control cells, promoting accumulation of nine 14α-methyl sterols. Based on these results, we propose a schematic model of sterol biosynthesis pathways in S. schenckii and S. brasiliensis. Effects on cell morphology due to 24-SMT inhibition by H3 as analyzed by SEM and TEM included irregular cell shape, reduced cytoplasmic electron-density, and reduced thickness of the microfibrillar cell wall layer. Moreover, 24-SMT inhibition by H3 promoted mitochondrial disturbance, as demonstrated by alterations in MitoTracker(®) Red CMXRos fluorescence intensity evaluated by flow cytometry. When used in conjunction with itraconazole, H3 enhanced the effectiveness of itraconazole against all tested strains, reducing at least half (or more) the MIC values of itraconazole. In addition, cytotoxicity assays revealed that H3 was more selective toward these fungi than was itraconazole. Thus, 24-SMT inhibition by H3 was an effective antifungal strategy against S. schenckii and S. brasiliensis. Inhibition of the methylation reaction catalyzed by 24-SMT has a strong antiproliferative effect via disruption of ergosterol homeostasis

  13. Translesion Synthesis: Insights into the Selection and Switching of DNA Polymerases

    PubMed Central

    Zhao, Linlin; Washington, M. Todd

    2017-01-01

    DNA replication is constantly challenged by DNA lesions, noncanonical DNA structures and difficult-to-replicate DNA sequences. Two major strategies to rescue a stalled replication fork and to ensure continuous DNA synthesis are: (1) template switching and recombination-dependent DNA synthesis; and (2) translesion synthesis (TLS) using specialized DNA polymerases to perform nucleotide incorporation opposite DNA lesions. The former pathway is mainly error-free, and the latter is error-prone and a major source of mutagenesis. An accepted model of translesion synthesis involves DNA polymerase switching steps between a replicative DNA polymerase and one or more TLS DNA polymerases. The mechanisms that govern the selection and exchange of specialized DNA polymerases for a given DNA lesion are not well understood. In this review, recent studies concerning the mechanisms of selection and switching of DNA polymerases in eukaryotic systems are summarized. PMID:28075396

  14. Hepatic entrapment of esterified cholesterol drives continual expansion of whole body sterol pool in lysosomal acid lipase-deficient mice.

    PubMed

    Aqul, Amal; Lopez, Adam M; Posey, Kenneth S; Taylor, Anna M; Repa, Joyce J; Burns, Dennis K; Turley, Stephen D

    2014-10-15

    Cholesteryl ester storage disease (CESD) results from loss-of-function mutations in LIPA, the gene that encodes lysosomal acid lipase (LAL). Hepatomegaly and deposition of esterified cholesterol (EC) in multiple organs ensue. The present studies quantitated rates of synthesis, absorption, and disposition of cholesterol, and whole body cholesterol pool size in a mouse model of CESD. In 50-day-old lal(-/-) and matching lal(+/+) mice fed a low-cholesterol diet, whole animal cholesterol content equalled 210 and 50 mg, respectively, indicating that since birth the lal(-/-) mice sequestered cholesterol at an average rate of 3.2 mg·day(-1)·animal(-1). The proportion of the body sterol pool contained in the liver of the lal(-/-) mice was 64 vs. 6.3% in their lal(+/+) controls. EC concentrations in the liver, spleen, small intestine, and lungs of the lal(-/-) mice were elevated 100-, 35-, 15-, and 6-fold, respectively. In the lal(-/-) mice, whole liver cholesterol synthesis increased 10.2-fold, resulting in a 3.2-fold greater rate of whole animal sterol synthesis compared with their lal(+/+) controls. The rate of cholesterol synthesis in the lal(-/-) mice exceeded that in the lal(+/+) controls by 3.7 mg·day(-1)·animal(-1). Fractional cholesterol absorption and fecal bile acid excretion were unchanged in the lal(-/-) mice, but their rate of neutral sterol excretion was 59% higher than in their lal(+/+) controls. Thus, in this model, the continual expansion of the body sterol pool is driven by the synthesis of excess cholesterol, primarily in the liver. Despite the severity of their disease, the median life span of the lal(-/-) mice was 355 days.

  15. Plant sterols in vegetables and fruits commonly consumed in Sweden.

    PubMed

    Normén, L; Johnsson, M; Andersson, H; van Gameren, Y; Dutta, P

    1999-04-01

    Plant sterols are known to have serum cholesterol lowering effects. A high dietary intake might therefore have a positive impact on health. All food items of vegetable origin contain some amount of plant sterols. The aim of this study was to analyse the plant sterol content of vegetables and fruits commonly consumed in Sweden, and to compare fresh and cooked samples of the same items. Altogether 20 different vegetables and 14 fruits were analysed. All vegetables and fruits were purchased in two shops in the city of Gothenburg, Sweden. Lyophilization was performed within one month of the items being purchased. The samples were frozen at -20 (C and analysed within six months, with a GLC method after acid hydrolysis, alkaline hydrolysis and silylation with tri-methylsilylether. The acid hydrolysis was done in order to detect the fraction of glycosylated plant sterols, which are split during boiling with HCl. The median plant sterol content of vegetables was 14 (3.8-50) mg/100 g edible portion. The highest concentrations were found in broccoli. Brussels sprouts, cauliflower and olives. The median plant sterol content of fruits was 16 (3-44) mg/100 g edible portion. The highest concentrations were found in oranges and passion fruits. The plant sterol concentrations were thus low in vegetables and fruits commonly consumed in Sweden. A serum cholesterol lowering effect attributed to the plant sterols in vegetables and fruits would therefore be of limited significance.

  16. Composition of Plant Sterols and Stanols in Supplemented Food Products.

    PubMed

    Moreau, Robert A

    2015-01-01

    All fruits, vegetables, grains and other plant materials contain small amounts of plant sterols, which are essential for the function of the biological membranes in living cells. The average human consumption of plant sterols has been estimated to be about 150-350 mg/day and trace amounts of stanols (which are defined as saturated sterols such as sitostanol), but this number varies regionally and is higher for vegetarians. When consumed in the diet, plant sterols reduce the levels of serum cholesterol. In 1995 the first functional food product, Benecol spread (enriched in plant stanol fatty acid esters), was developed by Raisio and marketed, first in Finland and then globally. Since then many other functional food products have been developed and are now available globally. In addition to stanol esters, other functional food products contain plant sterol esters and/or free (unesterified) plant sterols and stanols. In essentially all of the current functional foods that are enriched in sterols and stanols, the feedstock from which the sterols and stanols are obtained is either tall oil (a byproduct/coproduct of the pulping of pine wood) or vegetable oil deodorizer distillate (a byproduct/coproduct of the refining of vegetable oils).

  17. Composition of plant sterols and stanols in supplemented food products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    All fruits, vegetables, grains and other plant materials contain small amounts of plant sterols, which are essential for the function of the biological membranes in living cells. The average human consumption of plant sterols has been estimated to be about 150-350 mg/day and trace amounts of stanol...

  18. STEROLS AS BIOMARKERS IN GYMNODINIUM BREVE DISTRIBUTION IN DINOFLAGELLATES

    EPA Science Inventory

    The sterol composition of marine microalgae has been shown to be a chemotaxonomic property potentially of value in distinguishing members of different algal classes. For example, members of the class Dinophyceae display sterol compositions ranging from as few as two (cholesterol ...

  19. Effects of plant sterols derived from Aloe vera gel on human dermal fibroblasts in vitro and on skin condition in Japanese women

    PubMed Central

    Tanaka, Miyuki; Misawa, Eriko; Yamauchi, Koji; Abe, Fumiaki; Ishizaki, Chiaki

    2015-01-01

    Background Aloe is known for its topical use for treating wounds and burns. Many previous studies reported the healing effects of Aloe vera. However, there are few clinical studies on the effect of orally administered A. vera gel on the skin. Aloe sterols are a type of plant sterols that have the capability to regulate the metabolism of glucose and lipids. In a recent study, we confirmed that ingested Aloe sterols reached the peripheral tissues through the bloodstream. However, their influence on dermal fibroblasts has not been investigated. Methods First, we investigated the capability of Aloe sterols (cycloartenol and lophenol) to stimulate human dermal fibroblasts in vitro. Then, we investigated the effect of intake of Aloe vera gel powder (AVGP) containing 40 μg Aloe sterols on the skin conditions in Japanese women with dry skin in a randomized, double-blind, placebo-controlled trial. Results After cocultivation with Aloe sterols, the production of collagen and hyaluronic acid increased by approximately two-fold and 1.5-fold, and gene expression levels of these enzymes responsible for their synthesis were also observed in human dermal fibroblasts. An increase in arm skin hydration was observed at 8 weeks in the AVGP group, whereas a slight decrease in arm skin hydration was noted in the placebo group. However, there was no statistical difference between AVGP and placebo groups in skin moisture. In subgroup analysis, the change in the mean wrinkle depth was significantly lower in the AVGP group than in the control group. In addition, percent body fat after 8 weeks was significantly lower in the AVGP group. No AVGP intake-dependent harmful phenomenon was observed during the intake period. Conclusion The present study confirms that daily oral Aloe sterol-containing AVGP significantly reduced facial wrinkles in women aged ≥40 years, and Aloe sterols stimulate collagen and hyaluronic acid production by human dermal fibroblasts. PMID:25759593

  20. Sterol Regulatory Element Binding Protein Is a Principal Regulator of Anaerobic Gene Expression in Fission Yeast†

    PubMed Central

    Todd, Bridget L.; Stewart, Emerson V.; Burg, John S.; Hughes, Adam L.; Espenshade, Peter J.

    2006-01-01

    Fission yeast sterol regulatory element binding protein (SREBP), called Sre1p, functions in an oxygen-sensing pathway to allow adaptation to fluctuating oxygen concentrations. The Sre1p-Scp1p complex responds to oxygen-dependent sterol synthesis as an indirect measure of oxygen availability. To examine the role of Sre1p in anaerobic gene expression in Schizosaccharomyces pombe, we performed transcriptional profiling experiments after a shift to anaerobic conditions for 1.5 h. Of the 4,940 genes analyzed, expression levels of 521 (10.5%) and 686 (13.9%) genes were significantly increased and decreased, respectively, under anaerobic conditions. Sre1p controlled 68% of genes induced ≥2-fold. Oxygen-requiring biosynthetic pathways for ergosterol, heme, sphingolipid, and ubiquinone were primary targets of Sre1p. Induction of glycolytic genes and repression of mitochondrial oxidative phosphorylation genes largely did not require Sre1p. Using chromatin immunoprecipitation, we demonstrated that Sre1p acts directly at target gene promoters and stimulates its own transcription under anaerobic conditions. sre1+ promoter analysis identified two DNA elements that are both necessary and sufficient for oxygen-dependent, Sre1p-dependent transcription. Interestingly, these elements are homologous to sterol regulatory elements bound by mammalian SREBP, highlighting the evolutionary conservation between Sre1p and SREBP. We conclude that Sre1p is a principal activator of anaerobic gene expression, upregulating genes required for nonrespiratory oxygen consumption. PMID:16537923

  1. Diversity of Sterol Composition in Tunisian Pistacia lentiscus Seed Oil.

    PubMed

    Mezni, Faten; Labidi, Arbia; Khouja, Mohamed Larbi; Martine, Lucy; Berdeaux, Olivier; Khaldi, Abdelhamid

    2016-05-01

    Pistacia lentiscus L. seed oil is used in some Mediterranean forest area for culinary and medicinal purposes. In this study, we aim to examine, for the first time, the effect of growing area on sterol content of Pistacia lentiscus seed oil. Fruits were harvested from 13 different sites located in northern and central Tunisia. Gas chromatography-flame-ionization detection (GC-FID) was used to quantify sterols and gas chromatography/mass spectrometry (GC/MS) was used to identify them. The major sterol identified was β-sitosterol with a value ranging from 854.12 to 1224.09 mg/kg of oil, thus making up more than 54% of the total sterols. The other two main sterols were cycloartenol (11%) and 24-methylene-cycloartenol (5%). Statistical results revealed that growing location significantly (P < 0.001) affected phytosterol levels in these oils.

  2. [THE SPIRIT CHOLESTEROL, BIOLOGICA L ROLE AT STAGES OF PHYLOGENESIS, MECHANISMS OF INHIBITION OF SYNTHESIS OF STEROL BY STATINS, FACTORS OF PHARMACOGENOMICS AND DIAGNOSTIC SIGNIFICANCE OF CHOLESTEROL OF LIPOPROTEINS OF LOW DENSITY].

    PubMed

    Titov, V N; Kotlovskii, M Yu; Pokrovskii, A A; Kotlovskaia, O S; Osedko, A V; Titova, N M; Kotlovskii, Yu V; Digaii, A M

    2015-04-01

    The hypolipidemic effect of statins is realized by inhibition of synthesis of local pool of cholesterol spirit in endoplasmic net of hepatocytes. The cholesterol spirit covers all hydrophobic medium of triglycerides with polar mono layer of phosphatidylcholines and cholesterol spirit prior to secretion of lipoproteins of very low density into hydrophilic medium. The lesser mono layer between lipase enzyme and triglycerides substrate contains of cholesterol spirit the higher are the parameters of hydrolysis of palmitic and oleic lipoproteins of very low density. The sequence of effect of statins is as follows: blocking of synthesis in hepatocytes and decreasing of content of unesterified cholesterol spirit in blood plasma; activation of hydrolysis of triglycerides in palmitic and oleic lipoproteins of very low density; formation of ligand lipoproteins of very low density and their absorption by cells by force of apoB-100 endocytosis; decreasing in blood of content of polyenoic fatty acids, equimolar esterified by cholesterol spirit, polyethers of cholesterol spirit and decreasing of level of cholesterol spirit-lipoproteins of very low density. There is no way to eliminate aphysiological effect of disordered biological function of trophology (nutrition) on metabolism of fatty acids in population by means of pharmaceuticals intake. It is necessary to eliminate aphysiological effect of environment. To decrease rate of diseases of cardiovascular system one has to decrease in food content of saturated fatty acids and in the first instance palmitic saturated fatty acid, trans-form fatty acid, palmitoleic fatty acids up to physiological values and increase to the same degree the content of polyenoic fatty acids. The saturated fatty acids block absorption of polyenoic fatty acids by cells. The atherosclerosis is a deficiency of polyenoic fatty acids under surplus of palmitic saturated fatty acid.

  3. ATP-binding cassette transporters and sterol O-acyltransferases interact at membrane microdomains to modulate sterol uptake and esterification.

    PubMed

    Gulati, Sonia; Balderes, Dina; Kim, Christine; Guo, Zhongmin A; Wilcox, Lisa; Area-Gomez, Estela; Snider, Jamie; Wolinski, Heimo; Stagljar, Igor; Granato, Juliana T; Ruggles, Kelly V; DeGiorgis, Joseph A; Kohlwein, Sepp D; Schon, Eric A; Sturley, Stephen L

    2015-11-01

    A key component of eukaryotic lipid homeostasis is the esterification of sterols with fatty acids by sterol O-acyltransferases (SOATs). The esterification reactions are allosterically activated by their sterol substrates, the majority of which accumulate at the plasma membrane. We demonstrate that in yeast, sterol transport from the plasma membrane to the site of esterification is associated with the physical interaction of the major SOAT, acyl-coenzyme A:cholesterol acyltransferase (ACAT)-related enzyme (Are)2p, with 2 plasma membrane ATP-binding cassette (ABC) transporters: Aus1p and Pdr11p. Are2p, Aus1p, and Pdr11p, unlike the minor acyltransferase, Are1p, colocalize to sterol and sphingolipid-enriched, detergent-resistant microdomains (DRMs). Deletion of either ABC transporter results in Are2p relocalization to detergent-soluble membrane domains and a significant decrease (53-36%) in esterification of exogenous sterol. Similarly, in murine tissues, the SOAT1/Acat1 enzyme and activity localize to DRMs. This subcellular localization is diminished upon deletion of murine ABC transporters, such as Abcg1, which itself is DRM associated. We propose that the close proximity of sterol esterification and transport proteins to each other combined with their residence in lipid-enriched membrane microdomains facilitates rapid, high-capacity sterol transport and esterification, obviating any requirement for soluble intermediary proteins.

  4. The effect of methyl jasmonate on triterpene and sterol metabolisms of Centella asiatica, Ruscus aculeatus and Galphimia glauca cultured plants.

    PubMed

    Mangas, Susana; Bonfill, Mercè; Osuna, Lidia; Moyano, Elisabeth; Tortoriello, Jaime; Cusido, Rosa M; Piñol, M Teresa; Palazón, Javier

    2006-09-01

    Considering that exogenously applied methyl jasmonate can enhance secondary metabolite production in a variety of plant species and that 2,3-oxidosqualene is a common precursor of triterpenes and sterols in plants, we have studied Centella asiatica and Galphimia glauca (both synthesizing triterpenoid secondary compounds) and Ruscus aculeatus (which synthesizes steroidal secondary compounds) for their growth rate and content of free sterols and respective secondary compounds, after culturing with or without 100 microM methyl jasmonate. Our results show that elicited plantlets of G. glauca and to a higher degree C. asiatica (up to 152-times more) increased their content of triterpenoids directly synthesized from 2,3-oxidosqualene (ursane saponins and nor-seco-friedelane galphimines, respectively) at the same time as growth decreased. In contrast, the free sterol content of C. asiatica decreased notably, and remained practically unaltered in G. glauca. However, in the case of R. aculeatus, which synthesizes steroidal saponins (mainly spirostane type) indirectly from 2,3-oxidosqualene after the latter is converted to the plant phytosterol-precursor cycloartenol, while the growth rate and free sterol content clearly decreased, the spirostane saponine content was virtually unchanged (aerial part) or somewhat lower (roots) in presence of the same elicitor concentration. Our results suggest that while methyl jasmonate may be used as an inducer of enzymes involved in the triterpenoid synthesis downstream from 2,3-oxidosqualene in both C. asiatica and G. glauca plantlets, in those of C. asiatica and R. aculeatus it inhibited the enzymes involved in sterol synthesis downstream from cycloartenol.

  5. Insights into Fourier Synthesis and Analysis: Part I--Using Simple Programs and Equipment.

    ERIC Educational Resources Information Center

    Moore, Guy S. M.

    1988-01-01

    Introduced is a unique generation method of Fourier series requiring simple mathematical skills and using computer programs. Discusses Fourier synthesis by microcomputer, and Fourier analysis with simple equipment. Shown are a circuit diagram, computer programs, monitor displays and tables of data. (YP)

  6. Determining Antifungal Target Sites in the Sterol Pathway of the Yeasts Candida and Saccharomyces

    DTIC Science & Technology

    1999-10-01

    sensitivity to the azoles. The erg6 mutants were shown to be hypersensitive to a number of sterol synthesis and metabolic inhibitors including terbinafine ...composition of the plasma membrane present in the erg6 mutants. The other compounds, however, show increased efficiency of inhibition. Terbinafine , an...15 fHol ]-A3 YPD Nystatin 10 jig/mL Clotrimazole 1.0 gg/m Ketoconazole 1.0 gig/mL Tridemorph 0.03 jig/mL Terbinafine 1 ttg/mL Brefeldin A 1 lgg/mL

  7. Lathosterol to cholesterol ratio in serum predicts cholesterol lowering response to plant sterol consumption in a dual center, randomized, single-blind placebo controlled trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Benefits of plant sterols (PS) for cholesterol lowering are compromised by large variability in efficacy across individuals. High fractional cholesterol synthesis measured by deuterium incorporation has been associated with non-response to PS consumption; however, prospective studies showing this as...

  8. ATP-binding cassette transporters and sterol O-acyltransferases interact at membrane microdomains to modulate sterol uptake and esterification

    PubMed Central

    Gulati, Sonia; Balderes, Dina; Kim, Christine; Guo, Zhongmin A.; Wilcox, Lisa; Area-Gomez, Estela; Snider, Jamie; Wolinski, Heimo; Stagljar, Igor; Granato, Juliana T.; Ruggles, Kelly V.; DeGiorgis, Joseph A.; Kohlwein, Sepp D.; Schon, Eric A.; Sturley, Stephen L.

    2015-01-01

    A key component of eukaryotic lipid homeostasis is the esterification of sterols with fatty acids by sterol O-acyltransferases (SOATs). The esterification reactions are allosterically activated by their sterol substrates, the majority of which accumulate at the plasma membrane. We demonstrate that in yeast, sterol transport from the plasma membrane to the site of esterification is associated with the physical interaction of the major SOAT, acyl-coenzyme A:cholesterol acyltransferase (ACAT)-related enzyme (Are)2p, with 2 plasma membrane ATP-binding cassette (ABC) transporters: Aus1p and Pdr11p. Are2p, Aus1p, and Pdr11p, unlike the minor acyltransferase, Are1p, colocalize to sterol and sphingolipid-enriched, detergent-resistant microdomains (DRMs). Deletion of either ABC transporter results in Are2p relocalization to detergent-soluble membrane domains and a significant decrease (53–36%) in esterification of exogenous sterol. Similarly, in murine tissues, the SOAT1/Acat1 enzyme and activity localize to DRMs. This subcellular localization is diminished upon deletion of murine ABC transporters, such as Abcg1, which itself is DRM associated. We propose that the close proximity of sterol esterification and transport proteins to each other combined with their residence in lipid-enriched membrane microdomains facilitates rapid, high-capacity sterol transport and esterification, obviating any requirement for soluble intermediary proteins.—Gulati, S., Balderes, D., Kim, C., Guo, Z. A., Wilcox, L., Area-Gomez, E., Snider, J., Wolinski, H., Stagljar, I., Granato, J. T., Ruggles, K. V., DeGiorgis, J. A., Kohlwein, S. D., Schon, E. A., Sturley, S. L. ATP-binding cassette transporters and sterol O-acyltransferases interact at membrane microdomains to modulate sterol uptake and esterification. PMID:26220175

  9. Comparison of Enzymatic Hydrolysis and Acid Hydrolysis of Sterol Glycosides from Foods Rich in Δ(7)-Sterols.

    PubMed

    Münger, Linda H; Jutzi, Sabrina; Lampi, Anna-Maija; Nyström, Laura

    2015-08-01

    In this study, we present the difference in sterol composition of extracted steryl glycosides (SG) hydrolyzed by either enzymatic or acid hydrolysis. SG were analyzed from foods belonging to the plant families Cucurbitaceae (melon and pumpkin seeds) and Amaranthaceae (amaranth and beetroot), both of which are dominated by Δ(7)-sterols. Released sterols were quantified by gas chromatography with a flame ionization detector (GC-FID) and identified using gas chromatography/mass spectrometry (GC-MS). All Δ(7)-sterols identified (Δ(7)-stigmastenyl, spinasteryl, Δ(7)-campesteryl, Δ(7)-avenasteryl, poriferasta-7,25-dienyl and poriferasta-7,22,25-trienyl glucoside) underwent isomerization under acidic conditions and high temperature. Sterols with an ethylidene or methylidene side chain were found to form multiple artifacts. The artifact sterols coeluted with residues of incompletely isomerized Δ(7)-sterols, or Δ(5)-sterols if present, and could be identified as Δ(8(14))-sterols on the basis of relative retention time, and their MS spectra as trimethylsilyl (TMS) and acetate derivatives. For instance, SG from melon were composed of 66% Δ(7)-stigmastenol when enzymatic hydrolysis was performed, whereas with acid hydrolysis only 8% of Δ(7)-stigmastenol was determined. The artifact of Δ(7)-stigmastenol coeluted with residual non-isomerized spinasterol, demonstrating the high risk of misinterpretation of compositional data obtained after acid hydrolysis. Therefore, the accurate composition of SG from foods containing sterols with a double bond at C-7 can only be obtained by enzymatic hydrolysis or by direct analysis of the intact SG.

  10. Rhodium-Catalyzed Synthesis of Chiral Spiro-9-silabifluorenes by Dehydrogenative Silylation: Mechanistic Insights into the Construction of Tetraorganosilicon Stereocenters.

    PubMed

    Murai, Masahito; Takeuchi, Yutaro; Yamauchi, Kanae; Kuninobu, Yoichiro; Takai, Kazuhiko

    2016-04-18

    Mechanistic insight into the construction of quaternary silicon chiral centers by rhodium-catalyzed synthesis of spiro-9-silabifluorenes through dehydrogenative silylation is reported. The C2 -symmetric bisphosphine ligand, BINAP, was effective in controlling enantioselectivity, and axially chiral spiro-9-silabifluorenes were obtained in excellent yields with high enantiomeric excess. Monitoring of the reaction revealed the presence of a monohydrosilane intermediate as a mixture of two constitutional isomers. The reaction proceeded through two consecutive dehydrogenative silylations, and the absolute configuration was determined in the first silylative cyclization. Competitive reactions with electron-rich and electron-deficient dihydrosilanes indicated that the rate of silylative cyclization increased with decreasing electron density on the silicon atom of the starting dihydrosilane. Further investigation disclosed a rare interconversion between the two constitutional isomers of the monohydrosilane intermediate with retention of the absolute configuration.

  11. Design, synthesis and insight into the structure-activity relationship of 1,3-disubstituted indazoles as novel HIF-1 inhibitors.

    PubMed

    An, Hongchan; Kim, Nam-Jung; Jung, Jong-Wha; Jang, Hannah; Park, Jong-Wan; Suh, Young-Ger

    2011-11-01

    Design, synthesis and insight into the structure-activity relationship (SAR) of 1,3-disubstituted indazoles as novel HIF-1 inhibitors are described. In particular, the substituted furan moiety on indazole skeleton as well as its substitution pattern turns out crucial for the high HIF-1 inhibition.

  12. Mutations in the human SC4MOL gene encoding a methyl sterol oxidase cause psoriasiform dermatitis, microcephaly, and developmental delay

    PubMed Central

    He, Miao; Kratz, Lisa E.; Michel, Joshua J.; Vallejo, Abbe N.; Ferris, Laura; Kelley, Richard I.; Hoover, Jacqueline J.; Jukic, Drazen; Gibson, K. Michael; Wolfe, Lynne A.; Ramachandran, Dhanya; Zwick, Michael E.; Vockley, Jerry

    2011-01-01

    Defects in cholesterol synthesis result in a wide variety of symptoms, from neonatal lethality to the relatively mild dysmorphic features and developmental delay found in individuals with Smith-Lemli-Opitz syndrome. We report here the identification of mutations in sterol-C4-methyl oxidase–like gene (SC4MOL) as the cause of an autosomal recessive syndrome in a human patient with psoriasiform dermatitis, arthralgias, congenital cataracts, microcephaly, and developmental delay. This gene encodes a sterol-C4-methyl oxidase (SMO), which catalyzes demethylation of C4-methylsterols in the cholesterol synthesis pathway. C4-Methylsterols are meiosis-activating sterols (MASs). They exist at high concentrations in the testis and ovary and play roles in meiosis activation. In this study, we found that an accumulation of MASs in the patient led to cell overproliferation in both skin and blood. SMO deficiency also substantially altered immunocyte phenotype and in vitro function. MASs serve as ligands for liver X receptors α and β (LXRα and LXRβ), which are important in regulating not only lipid transport in the epidermis, but also innate and adaptive immunity. Deficiency of SMO represents a biochemical defect in the cholesterol synthesis pathway, the clinical spectrum of which remains to be defined. PMID:21285510

  13. Fecal Sterol and Runoff Analysis for Nonpoint Source Tracking.

    PubMed

    Fahrenfeld, N L; Del Monaco, N; Coates, J T; Elzerman, A W

    2016-01-01

    Fecal pollution source identification is needed to quantify risk, target installation of source controls, and assess performance of best management practices in impaired surface waters. Sterol analysis is a chemical method for fecal source tracking that allows for differentiation between several fecal pollution sources. The objectives of this study were to use these chemical tracers for quantifying human fecal inputs in a mixed-land-use watershed without point sources of pollution and to determine the relationship between land use and sterol ratios. Fecal sterol analysis was performed on bed and suspended sediment from impaired streams. Human fecal signatures were found at sites with sewer overflow and septic inputs. Different sterol ratios used to indicate human fecal pollution varied in their sensitivity. Next, geospatial data was used to determine the runoff volumes associated with each land-use category in the watersheds. Fecal sterol ratios were compared between sampling locations and correlations were tested between ratio values and percentage of runoff for a given land-use category. Correlation was not observed between percentage of runoff from developed land and any of the five tested human-indicating sterol ratios in streambed sediments, confirming that human fecal inputs were not evenly distributed across the urban landscape. Several practical considerations for adopting this chemical method for microbial source tracking in small watersheds are discussed. Results indicate that sterol analysis is useful for identifying the location of human fecal nonpoint-source inputs.

  14. Sterols of a contemporary lacustrine sediment. [in English postglacial lake

    NASA Technical Reports Server (NTRS)

    Gaskell, S. J.; Eglinton, G.

    1976-01-01

    Results are reported for detailed sterol analyses of several depths (corresponding to between zero and about 150 yr in age) in a contemporary lacustrine sediment from a freshwater lake of postglacial origin in England. Delta 5-, delta 22-, and delta 5,22-sterols are identified along with 5 alpha- and 5 beta-stanols as well as a C26 stanol with a C7 side chain. Solvent extraction yields carbon number distributions for the 5 alpha- and 5 beta-stanol sediment constituents that parallel the corresponding delta 5-sterol distributions. The amounts of 5 alpha-stanols are found to exceed those of 5 beta-stanols in the sediment, and variations in the ratio of 5 alpha- to 5 beta-stanol between sediment samples from similar depths are shown to suggest an inhomogeneity of the sediment. It is found that the sterol composition of sediment cores varies markedly with depth, reflecting both the effects of a sterol hydrogenation process and a changing input to the sediment. It is concluded that C29 sterols, of probable higher-plant origin, predominate at lower sediment depths while C27 sterols, possibly derived from autochthonous sources, are more abundant in the surface sediment.

  15. Anatomical distribution of sterols in oysters (Crassostrea gigas).

    PubMed

    Gordon, D T; Collins, N

    1982-11-01

    Oysters (Crassostrea gigas) contain at least 8 predominant sterols as determined by gas liquid chromatography and a modified Liebermann-Burchard reaction. These sterols and the average amount found in mg/100 are: C26-sterol (22-trans-24-norcholesta-5, 22-diene-3 beta-ol), 19.1; 22-dehydrocholesterol, 15.1; cholesterol, 46.8; brassicasterol, 27.2; delta 5,7-sterols (i.e., 7-dehydrocholesterol) 22.5; 24-methylenecholesterol 29.1; 24-ethylcholesta-5,22-diene-3 beta-ol, 1.2; and 24-ethylcholesta-5-en-3 beta-ol, 12.7. The distribution of these sterols appears uniform (r2 = 0.938) between 5 major organs of the oyster. The percent body mass vs percent total sterols in these 5 organs are: mantle 44.1--41.4; visceral mass 30.3--36.7; gills 13.2--11.7; adductor muscle 8.3--3.7; and labial palps 4.2--6.5. The possible sources of these sterols are discussed.

  16. Chemical synthesis of erythropoietin glycoforms for insights into the relationship between glycosylation pattern and bioactivity

    PubMed Central

    Murakami, Masumi; Kiuchi, Tatsuto; Nishihara, Mika; Tezuka, Katsunari; Okamoto, Ryo; Izumi, Masayuki; Kajihara, Yasuhiro

    2016-01-01

    The role of sialyloligosaccharides on the surface of secreted glycoproteins is still unclear because of the difficulty in the preparation of sialylglycoproteins in a homogeneous form. We selected erythropoietin (EPO) as a target molecule and designed an efficient synthetic strategy for the chemical synthesis of a homogeneous form of five EPO glycoforms varying in glycosylation position and the number of human-type biantennary sialyloligosaccharides. A segment coupling strategy performed by native chemical ligation using six peptide segments including glycopeptides yielded homogeneous EPO glycopeptides, and folding experiments of these glycopeptides afforded the correctly folded EPO glycoforms. In an in vivo erythropoiesis assay in mice, all of the EPO glycoforms displayed biological activity, in particular the EPO bearing three sialyloligosaccharides, which exhibited the highest activity. Furthermore, we observed that the hydrophilicity and biological activity of the EPO glycoforms varied depending on the glycosylation pattern. This knowledge will pave the way for the development of homogeneous biologics by chemical synthesis. PMID:26824070

  17. Chemical synthesis of erythropoietin glycoforms for insights into the relationship between glycosylation pattern and bioactivity.

    PubMed

    Murakami, Masumi; Kiuchi, Tatsuto; Nishihara, Mika; Tezuka, Katsunari; Okamoto, Ryo; Izumi, Masayuki; Kajihara, Yasuhiro

    2016-01-01

    The role of sialyloligosaccharides on the surface of secreted glycoproteins is still unclear because of the difficulty in the preparation of sialylglycoproteins in a homogeneous form. We selected erythropoietin (EPO) as a target molecule and designed an efficient synthetic strategy for the chemical synthesis of a homogeneous form of five EPO glycoforms varying in glycosylation position and the number of human-type biantennary sialyloligosaccharides. A segment coupling strategy performed by native chemical ligation using six peptide segments including glycopeptides yielded homogeneous EPO glycopeptides, and folding experiments of these glycopeptides afforded the correctly folded EPO glycoforms. In an in vivo erythropoiesis assay in mice, all of the EPO glycoforms displayed biological activity, in particular the EPO bearing three sialyloligosaccharides, which exhibited the highest activity. Furthermore, we observed that the hydrophilicity and biological activity of the EPO glycoforms varied depending on the glycosylation pattern. This knowledge will pave the way for the development of homogeneous biologics by chemical synthesis.

  18. New insights into the electrochemical behavior of acid orange 7: Convergent paired electrochemical synthesis of new aminonaphthol derivatives

    PubMed Central

    Momeni, Shima; Nematollahi, Davood

    2017-01-01

    Electrochemical behavior of acid orange 7 has been exhaustively studied in aqueous solutions with different pH values, using cyclic voltammetry and constant current coulometry. This study has provided new insights into the mechanistic details, pH dependence and intermediate structure of both electrochemical oxidation and reduction of acid orange 7. Surprisingly, the results indicate that a same redox couple (1-iminonaphthalen-2(1H)-one/1-aminonaphthalen-2-ol) is formed from both oxidation and reduction of acid orange 7. Also, an additional purpose of this work is electrochemical synthesis of three new derivatives of 1-amino-4-(phenylsulfonyl)naphthalen-2-ol (3a–3c) under constant current electrolysis via electrochemical oxidation (and reduction) of acid orange 7 in the presence of arylsulfinic acids as nucleophiles. The results indicate that the electrogenerated 1-iminonaphthalen-2(1 H)-one participates in Michael addition reaction with arylsulfinic acids to form the 1-amino-3-(phenylsulfonyl)naphthalen-2-ol derivatives. The synthesis was carried out in an undivided cell equipped with carbon rods as an anode and cathode. PMID:28165049

  19. New insights into the electrochemical behavior of acid orange 7: Convergent paired electrochemical synthesis of new aminonaphthol derivatives.

    PubMed

    Momeni, Shima; Nematollahi, Davood

    2017-02-06

    Electrochemical behavior of acid orange 7 has been exhaustively studied in aqueous solutions with different pH values, using cyclic voltammetry and constant current coulometry. This study has provided new insights into the mechanistic details, pH dependence and intermediate structure of both electrochemical oxidation and reduction of acid orange 7. Surprisingly, the results indicate that a same redox couple (1-iminonaphthalen-2(1H)-one/1-aminonaphthalen-2-ol) is formed from both oxidation and reduction of acid orange 7. Also, an additional purpose of this work is electrochemical synthesis of three new derivatives of 1-amino-4-(phenylsulfonyl)naphthalen-2-ol (3a-3c) under constant current electrolysis via electrochemical oxidation (and reduction) of acid orange 7 in the presence of arylsulfinic acids as nucleophiles. The results indicate that the electrogenerated 1-iminonaphthalen-2(1 H)-one participates in Michael addition reaction with arylsulfinic acids to form the 1-amino-3-(phenylsulfonyl)naphthalen-2-ol derivatives. The synthesis was carried out in an undivided cell equipped with carbon rods as an anode and cathode.

  20. New insights into the electrochemical behavior of acid orange 7: Convergent paired electrochemical synthesis of new aminonaphthol derivatives

    NASA Astrophysics Data System (ADS)

    Momeni, Shima; Nematollahi, Davood

    2017-02-01

    Electrochemical behavior of acid orange 7 has been exhaustively studied in aqueous solutions with different pH values, using cyclic voltammetry and constant current coulometry. This study has provided new insights into the mechanistic details, pH dependence and intermediate structure of both electrochemical oxidation and reduction of acid orange 7. Surprisingly, the results indicate that a same redox couple (1-iminonaphthalen-2(1H)-one/1-aminonaphthalen-2-ol) is formed from both oxidation and reduction of acid orange 7. Also, an additional purpose of this work is electrochemical synthesis of three new derivatives of 1-amino-4-(phenylsulfonyl)naphthalen-2-ol (3a–3c) under constant current electrolysis via electrochemical oxidation (and reduction) of acid orange 7 in the presence of arylsulfinic acids as nucleophiles. The results indicate that the electrogenerated 1-iminonaphthalen-2(1 H)-one participates in Michael addition reaction with arylsulfinic acids to form the 1-amino-3-(phenylsulfonyl)naphthalen-2-ol derivatives. The synthesis was carried out in an undivided cell equipped with carbon rods as an anode and cathode.

  1. Terpenoids and sterols from some Japanese mushrooms.

    PubMed

    Yaoita, Yasunori; Kikuchi, Masao; Machida, Koichi

    2014-03-01

    Over the past twenty years, our research group has been studying the chemical constituents of mushrooms. From nineteen species, namely, Amanita virgineoides Bas (Amanitaceae), Daedaleopsis tricolor (Bull.: Fr.) Bond. et Sing. (Polyporaceae), Grifolafrondosa (Fr.) S. F. Gray (Polyporaceae), Hericium erinaceum (Bull.: Fr.) Pers. (Hericiaceae), Hypsizigus marmoreus (Peck) Bigelow (Tricholomataceae), Lactarius piperatus (Scop.: Fr.) S. F. Gray (Russulaceae), Lentinula edodes (Berk.) Sing. (Pleurotaceae), Lyophyllyum connatum (Schum.: Fr.) Sing. (Tricholomataceae), Naematoloma sublateritium (Fr.) Karst. (Strophariaceae), Ompharia lapidescens Schroeter (Polyporaceae), Panellus serotinus (Pers.: Fr.) Kuhn. (Tricholomataceae), Pholiota nameko (T. Ito) S. Ito et Imai in Imai (Strophariaceae), Pleurotus eringii (DC.: Fr.) Quel. (Pleurotaceae), Polyporus umbellatus Fries (Polyporaceae), Russula delica Fr. (Russulaceae), Russula sanguinea (Bull.) Fr. (Russulaceae), Sarcodon aspratus (Berk.) S. Ito (Thelephoraceae), Tricholoma matsutake (S. Ito et Imai) Sing. (Tricholomataceae), and Tricholomaportentosum (Fr.) Quel. (Tricholomataceae), we isolated eight new sesquiterpenoids, six new meroterpenoids, three new triterpenoids, and twenty eight new sterols. In this review, structural features of these new compounds are discussed.

  2. Synthesis, biological characterization and molecular modeling insights of spirochromanes as potent HDAC inhibitors.

    PubMed

    Thaler, Florian; Moretti, Loris; Amici, Raffaella; Abate, Agnese; Colombo, Andrea; Carenzi, Giacomo; Fulco, Maria Carmela; Boggio, Roberto; Dondio, Giulio; Gagliardi, Stefania; Minucci, Saverio; Sartori, Luca; Varasi, Mario; Mercurio, Ciro

    2016-01-27

    In the last decades, inhibitors of histone deacetylases (HDAC) have become an important class of anti-cancer agents. In a previous study we described the synthesis of spiro[chromane-2,4'-piperidine]hydroxamic acid derivatives able to inhibit histone deacetylase enzymes. Herein, we present our exploration for new derivatives by replacing the piperidine moiety with various cycloamines. The goal was to obtain highly potent compounds with a good in vitro ADME profile. In addition, molecular modeling studies unravelled the binding mode of these inhibitors.

  3. Structural and Mechanistic Insight into the Listeria monocytogenes Two-enzyme Lipoteichoic Acid Synthesis System*

    PubMed Central

    Campeotto, Ivan; Percy, Matthew G.; MacDonald, James T.; Förster, Andreas; Freemont, Paul S.; Gründling, Angelika

    2014-01-01

    Lipoteichoic acid (LTA) is an important cell wall component required for proper cell growth in many Gram-positive bacteria. In Listeria monocytogenes, two enzymes are required for the synthesis of this polyglycerolphosphate polymer. The LTA primase LtaPLm initiates LTA synthesis by transferring the first glycerolphosphate (GroP) subunit onto the glycolipid anchor and the LTA synthase LtaSLm extends the polymer by the repeated addition of GroP subunits to the tip of the growing chain. Here, we present the crystal structures of the enzymatic domains of LtaPLm and LtaSLm. Although the enzymes share the same fold, substantial differences in the cavity of the catalytic site and surface charge distribution contribute to enzyme specialization. The eLtaSLm structure was also determined in complex with GroP revealing a second GroP binding site. Mutational analysis confirmed an essential function for this binding site and allowed us to propose a model for the binding of the growing chain. PMID:25128528

  4. Sterol Profile for Natural Juices Authentification by GC-MS

    SciTech Connect

    Culea, M.

    2007-04-23

    A GC-MS analytical method is described for some natural juices analysis. The fingerprint of sterols was used to characterize the natural juice. A rapid liquid-liquid extraction method was used. The sterols were separated on a Rtx-5MS capillary column, 15mx0.25mm, 0.25{mu}m film thickness, in a temperature program from 50 deg. C for 1 min, then ramped at 15 deg. C/min to 300 deg. C and held for 15 min. Identification of sterols and their patterns were used for juice characterization. The sterol profile is a useful approach for confirming the presence of juices of orange, grapefruit, pineapple and passion fruit in compounded beverages and for detecting of adulteration of fruit juices.

  5. Free and glycosylated sterol bioaccumulation in developing Cycas micronesica seeds.

    PubMed

    Marler, Thomas E; Shaw, Christopher A

    2009-07-15

    The bioaccumulation of free and glycosylated forms of stigmasterol and β-sitosterol were determined from Cycas micronesica K.D. Hill seeds throughout seed ontogeny. Per-seed pool of the four compounds increased linearly from 2 to 24 months, indicating no developmental period elicited a major shift in the rate of bioaccumulation. The slopes were not homogeneous, signifying a change in relative sterol profile concomitant with seed maturation. This shift was in favour of the glucosides, as their rate of accumulation exceeded that of the free sterols. Stigmasterol content exceeded that of β-sitosterol, but ontogeny did not influence the ratio of these dominant sterols. The quantity and quality of sterol exposure during consumption of foods prepared from gametophytes by humans is strongly influenced by age of harvested seeds. Results are critical for a further understanding of the link between human neurodegenerative diseases and historical consumption of foods derived from the seed gametophyte tissue.

  6. Sterol Profile for Natural Juices Authentification by GC-MS

    NASA Astrophysics Data System (ADS)

    Culea, M.

    2007-04-01

    A GC-MS analytical method is described for some natural juices analysis. The fingerprint of sterols was used to characterize the natural juice. A rapid liquid-liquid extraction method was used. The sterols were separated on a Rtx-5MS capillary column, 15m×0.25mm, 0.25μm film thickness, in a temperature program from 50°C for 1 min, then ramped at 15°C/min to 300°C and held for 15 min. Identification of sterols and their patterns were used for juice characterization. The sterol profile is a useful approach for confirming the presence of juices of orange, grapefruit, pineapple and passion fruit in compounded beverages and for detecting of adulteration of fruit juices.

  7. Digitonide precipitable sterols: a reevaluation with special attention to lanosterol

    SciTech Connect

    Cenedella, R.J.

    1982-06-01

    The ability of digitonin to precipitate lanosterol from prepared mixtures and biological sources was evaluated. Commercially available lanosterol was determined to be composed of about 60% lanosterol and 40% dihydrolanosterol. Both sterols were only partially precipitated by digitonin under all conditions examined. The presence of cholesterol increased the precipitation of lanosterol, but never to completion. About 40% of the lanosterols from saponified sheep's-wool fat was not precipitated by digitonin. Also /sup 14/C-labeled lanosterol recovered from rat brain following intracerebral injection of 2-(/sup 14/C)mevalonate was only 70% precipitated by digitonin. Steric hinderance by the methyl groups at carbon -4 is suggesed to explain the poor precipitability of this sterol. In conclusion, lanosterol can not be considered to be a digitonide-precipitable sterol equivalent to cholesterol. Caution should be exercised in situations where digitonin-precipitable sterols are being prepared from sources containing significant concentrations of lanosterol (i.e., mass and/or radiolabel).

  8. Characteristics of a new sterol-nonrequiring Mycoplasma.

    PubMed

    Tully, J G; Razin, S

    1969-06-01

    Two Mycoplasma strains recovered from tissue culture environments were found to grow in complex media devoid of serum or serum fractions containing cholesterol and in a cholesterol-free synthetic medium. Neither strain was capable of synthesizing pigmented carotenoids, although these compounds are present in, and characteristic of, other sterol-nonrequiring mycoplasmas. Serological tests and an analysis of their cell protein patterns obtained by gel electrophoresis indicated that the isolates were similar to each other but distinct from other sterol-nonrequiring serotypes, Mycoplasma laidlawii and M. granularum, as well as from sterol-requiring species. The existence of Mycoplasma other than M. laidlawii and M. granularum without sterol requirements suggested the need for some taxonomic changes in this group of organisms.

  9. Effect of sterol metabolism in the yeast-Drosophila system on the frequency of radiation-induced aneuploidy in the Drosophila melanogaster oocytes

    SciTech Connect

    Savitskii, V.V.; Luchnikova, E.M.; Inge-Vechtomov, S.G.

    1986-01-01

    The effect of sterol metabolism on induced mutagenesis of Drosophila melanogaster was studied in the ecogenetic system of yeast-Drosophila. Sterol deficiency was created in Drosophila by using the biomass of live cells of Saccharomyces cerevisiae strain 9-2-P712 till mutation in locus nys/sup r1/ blocking the synthesis of ergosterol as the food. It was found that rearing of Drosophila females on the mutant yeast increases the frequency of loss and nondisjunction of X chromosomes induced in mature oocytes by X rays (1000 R). Addition of 0.1% of cholesterol solution in 10% ethanol to the yeast biomass restores the resistance of oocyte to X irradiation to the control level. The possible hormonal effect on membrane leading to increased radiation-induced aneuploidy in Drosophila and the role of sterol metabolism in determining the resistance to various damaging factors are discussed.

  10. Suppressing Farnesyl Diphosphate Synthase Alters Chloroplast Development and Triggers Sterol-Dependent Induction of Jasmonate- and Fe-Related Responses.

    PubMed

    Manzano, David; Andrade, Paola; Caudepón, Daniel; Altabella, Teresa; Arró, Montserrat; Ferrer, Albert

    2016-09-01

    Farnesyl diphosphate synthase (FPS) catalyzes the synthesis of farnesyl diphosphate from isopentenyl diphosphate and dimethylallyl diphosphate. Arabidopsis (Arabidopsis thaliana) contains two genes (FPS1 and FPS2) encoding FPS. Single fps1 and fps2 knockout mutants are phenotypically indistinguishable from wild-type plants, while fps1/fps2 double mutants are embryo lethal. To assess the effect of FPS down-regulation at postembryonic developmental stages, we generated Arabidopsis conditional knockdown mutants expressing artificial microRNAs devised to simultaneously silence both FPS genes. Induction of silencing from germination rapidly caused chlorosis and a strong developmental phenotype that led to seedling lethality. However, silencing of FPS after seed germination resulted in a slight developmental delay only, although leaves and cotyledons continued to show chlorosis and altered chloroplasts. Metabolomic analyses also revealed drastic changes in the profile of sterols, ubiquinones, and plastidial isoprenoids. RNA sequencing and reverse transcription-quantitative polymerase chain reaction transcriptomic analysis showed that a reduction in FPS activity levels triggers the misregulation of genes involved in biotic and abiotic stress responses, the most prominent one being the rapid induction of a set of genes related to the jasmonic acid pathway. Down-regulation of FPS also triggered an iron-deficiency transcriptional response that is consistent with the iron-deficient phenotype observed in FPS-silenced plants. The specific inhibition of the sterol biosynthesis pathway by chemical and genetic blockage mimicked these transcriptional responses, indicating that sterol depletion is the primary cause of the observed alterations. Our results highlight the importance of sterol homeostasis for normal chloroplast development and function and reveal important clues about how isoprenoid and sterol metabolism is integrated within plant physiology and development.

  11. SURVEY OF THE STEROL COMPOSITION OF THE MARINE DINOFLAGELLATES KARENIA BREVIS, KARENIA MIKIMOTOI, AND KARLODINIUM MICRUM: DISTRIBUTION OF STEROLS WITHIN OTHER MEMBERS OF THE CLASS DINOPHYCEAE

    EPA Science Inventory

    The sterol composition of different marine microalgae was examined to determine the utility of sterols as biomarkers to distinguish members of various algal classes. For example, members of the class Dinophyceae possess certain 4-methyl sterols, such as dinosterol, which are rare...

  12. Osh proteins regulate membrane sterol organization but are not required for sterol movement between the ER and PM

    PubMed Central

    Georgiev, Alexander; Sullivan, David P.; Kersting, Michael C.; Dittman, Jeremy S.; Beh, Christopher T.; Menon, Anant K.

    2011-01-01

    Sterol transport between the endoplasmic reticulum (ER) and plasma membrane (PM) occurs by an ATP-dependent, non-vesicular mechanism that is presumed to require sterol transport proteins (STPs). In Saccharomyces cerevisiae, homologues of the mammalian oxysterol-binding protein (Osh1–7) have been proposed to function as STPs. To evaluate this proposal we took two approaches. First we used dehydroergosterol (DHE) to visualize sterol movement in living cells by fluorescence microscopy. DHE was introduced into the PM under hypoxic conditions and observed to redistribute to lipid droplets on growing the cells aerobically. Redistribution required ATP and the sterol acyltransferase Are2, but did not require PM-derived transport vesicles. DHE redistribution occurred robustly in a conditional yeast mutant (oshΔ osh4-1ts) that lacks all functional Osh proteins at 37°C. In a second approach we used a pulse-chase protocol to analyze the movement of metabolically radiolabeled ergosterol from the ER to the PM. Arrival of radiolabeled ergosterol at the PM was assessed in isolated PM-enriched fractions as well by extracting sterols from intact cells with methyl-β-cyclodextrin. These experiments revealed that whereas ergosterol is transported effectively from the ER to the PM in Osh-deficient cells, the rate at which it moves within the PM to equilibrate with the methyl-β-cyclodextrin extractable sterol pool is slowed. We conclude (i) that the role of Osh proteins in nonvesicular sterol transport between the PM, ER and lipid droplets is either minimal, or subsumed by other mechanisms and (ii) that Osh proteins regulate the organization of sterols at the PM. PMID:21689253

  13. Expression of SREBP-1c Requires SREBP-2-mediated Generation of a Sterol Ligand for LXR in Livers of Mice

    PubMed Central

    Rong, Shunxing; Cortés, Víctor A; Rashid, Shirya; Anderson, Norma N; McDonald, Jeffrey G; Liang, Guosheng; Moon, Young-Ah; Hammer, Robert E; Horton, Jay D

    2017-01-01

    The synthesis of cholesterol and fatty acids (FA) in the liver is independently regulated by SREBP-2 and SREBP-1c, respectively. Here, we genetically deleted Srebf-2 from hepatocytes and confirmed that SREBP-2 regulates all genes involved in cholesterol biosynthesis, the LDL receptor, and PCSK9; a secreted protein that degrades LDL receptors in the liver. Surprisingly, we found that elimination of Srebf-2 in hepatocytes of mice also markedly reduced SREBP-1c and the expression of all genes involved in FA and triglyceride synthesis that are normally regulated by SREBP-1c. The nuclear receptor LXR is necessary for Srebf-1c transcription. The deletion of Srebf-2 and subsequent lower sterol synthesis in hepatocytes eliminated the production of an endogenous sterol ligand required for LXR activity and SREBP-1c expression. These studies demonstrate that cholesterol and FA synthesis in hepatocytes are coupled and that flux through the cholesterol biosynthetic pathway is required for the maximal SREBP-1c expression and high rates of FA synthesis. DOI: http://dx.doi.org/10.7554/eLife.25015.001 PMID:28244871

  14. Lanostane triterpenoids and sterols from Antrodia camphorata.

    PubMed

    Huang, Hui-Chi; Liaw, Chih-Chuang; Yang, Hsin-Ling; Hseu, You-Cheng; Kuo, Hsiou-Ting; Tsai, Yao-Ching; Chien, Shih-Chang; Amagaya, Sakae; Chen, Yu-Chang; Kuo, Yueh-Hsiung

    2012-12-01

    Four lanostane triterpenes, 3,7,11-trioxo-5α-lanosta-8,24(E)-dien-26-oic acid, methyl 11α-3,7-dioxo-5α-lanosta-8,24(E)-dien-26-oate, methyl 3,7,11,12,15,23-hexaoxo-5α-lanost-8-en-26-oate, and ethyl 3,7,11,12,15,23-hexaoxo-5α-lanost-8-en-26-oate, two sterols, (14α,22E)-14-hydroxyergosta-7,22-diene-3,6-dione and a steroid named as camphosterol A were isolated from a mixture of fruiting bodies and mycelia of solid cultures of Antrodia camphorata. The ¹H and ¹³C NMR spectra of all compounds were fully assigned using a combination of 2D NMR experiments, including COSY, HMQC, HMBC and NOESY sequences. Six compounds were evaluated for cytotoxicity against several human tumor cell lines, all of which has moderate activity.

  15. Sterol composition of phaeodactylum tricornutum as influenced by growth temperature and light spectral quality.

    PubMed

    Véron, B; Billard, C; Dauguet, J C; Hartmann, M A

    1996-09-01

    In a detailed sterol analysis of the marine diatom Phaeodactylum tricornutum, free sterols as well as esterified and glycosylated conjugates were found. When the alga was grown under standard conditions (i.e., at 13 degrees C under white light), 64% of total sterols were steryl glycosides. In all sterol classes, except steryl esters, (24S)-24-methylcholesta-5,22E-dien-3 beta-ol (epibrassicasterol) was the major (80 to 99%) sterol component. Eight other sterols were identified. Growth under different light spectral quality (red, blue, yellow, and green) at 13 and 23 degrees C was examined. At 23 degrees C, a dramatic decrease in total sterol content was observed, especially under blue light. The distribution of sterols between free and conjugated forms as well as sterol profile inside each class was found to be strongly dependent on the light spectral quality at both temperatures.

  16. Synthesis of β-galactosylamides as ligands of the peanut lectin. Insights into the recognition process.

    PubMed

    Cano, María Emilia; Varela, Oscar; García-Moreno, María Isabel; García Fernández, José Manuel; Kovensky, José; Uhrig, María Laura

    2017-03-23

    The synthesis of mono and divalent β-galactosylamides linked to a hydroxylated chain having a C2 symmetry axis derived from l-tartaric anhydride is reported. Reference compounds devoid of hydroxyl groups in the linker were also prepared from β-galactosylamine and succinic anhydride. After functionalization with an alkynyl residue, the resulting building blocks were grafted onto different azide-equipped scaffolds through the copper catalyzed azide-alkyne cycloaddition. Thus, a family of structurally related mono and divalent β-N-galactopyranosylamides was obtained and fully characterized. The binding affinities of the ligands towards the model lectin PNA were measured by the enzyme-linked lectin assay (ELLA). The IC50 values were significantly higher than that of galactose but the presence of hydroxyl groups in the aglycone chain improved lectin recognition. Docking and molecular dynamics experiments were in accordance with the hypothesis that a hydroxyl group properly disposed in the linker could mimic the Glc O3 in the recognition process. On the other hand, divalent presentation of the ligands led to lectin affinity enhancements.

  17. Recharacterization of ancient DNA miscoding lesions: insights in the era of sequencing-by-synthesis.

    PubMed

    Gilbert, M Thomas P; Binladen, Jonas; Miller, Webb; Wiuf, Carsten; Willerslev, Eske; Poinar, Hendrik; Carlson, John E; Leebens-Mack, James H; Schuster, Stephan C

    2007-01-01

    Although ancient DNA (aDNA) miscoding lesions have been studied since the earliest days of the field, their nature remains a source of debate. A variety of conflicting hypotheses exist about which miscoding lesions constitute true aDNA damage as opposed to PCR polymerase amplification error. Furthermore, considerable disagreement and speculation exists on which specific damage events underlie observed miscoding lesions. The root of the problem is that it has previously been difficult to assemble sufficient data to test the hypotheses, and near-impossible to accurately determine the specific strand of origin of observed damage events. With the advent of emulsion-based clonal amplification (emPCR) and the sequencing-by-synthesis technology this has changed. In this paper we demonstrate how data produced on the Roche GS20 genome sequencer can determine miscoding lesion strands of origin, and subsequently be interpreted to enable characterization of the aDNA damage behind the observed phenotypes. Through comparative analyses on 390,965 bp of modern chloroplast and 131,474 bp of ancient woolly mammoth GS20 sequence data we conclusively demonstrate that in this sample at least, a permafrost preserved specimen, Type 2 (cytosine-->thymine/guanine-->adenine) miscoding lesions represent the overwhelming majority of damage-derived miscoding lesions. Additionally, we show that an as yet unidentified guanine-->adenine analogue modification, not the conventionally argued cytosine-->uracil deamination, underpins a significant proportion of Type 2 damage. How widespread these implications are for aDNA will become apparent as future studies analyse data recovered from a wider range of substrates.

  18. Hollow alloy nanostructures templated by Au nanorods: synthesis, mechanistic insights, and electrocatalytic activity.

    PubMed

    Xue, Mengmeng; Tan, Yiwei

    2014-11-07

    A unique methodology having access to Au nanorods (AuNRs)-based hollow alloy nanostructures has been developed. The syntheses and characterization of the hollow Pt-Au nanoalloys with ellipsoidal and cylindrical shapes together with a rattle-type hollow Cu-Au nanoheterostructure are described. Unlike the conventional nanoscale Kirkendall process, the formation of these AuNRs-based hollow nanostructures occurs under extremely mild conditions, indicating a distinctive underlying mechanism. The key step for this present synthesis method is the incubation of AuNRs with CuCl2 at 60 °C in the presence of hexadecyltrimethylammonium bromide (CTAB) or hexadecyltrimethylammonium chloride (CTAC). The selective etching of the tips of AuNRs caused by Cu(2+) ions combined with the dissolved molecular oxygen promotes the generation of defects and vacancies, leading to a facile alloying reaction by the crystal fusion of AuNRs. Particularly, the results of the formation of the hollow nanoalloys in conjunction with various control experiments demonstrate that the halide ions that are specifically adsorbed on the AuNR surface afford sinks for vacancy accumulation and condensation during the unbalanced interdiffusion of alloying atoms, presumably because of the disproportion in the equilibrium concentration of vacancies. Thus, the void formation becomes kinetically favorable. The Pt-Au nanocages can provide modified surface electronic structures, resulting from their non-uniform crystalline structures and the surface segregation of Pt in the nanocages. These characteristics enable them to exhibit excellent electrocatalytic performance for the oxygen reduction reaction (ORR).

  19. Identifying avian sources of faecal contamination using sterol analysis.

    PubMed

    Devane, Megan L; Wood, David; Chappell, Andrew; Robson, Beth; Webster-Brown, Jenny; Gilpin, Brent J

    2015-10-01

    Discrimination of the source of faecal pollution in water bodies is an important step in the assessment and mitigation of public health risk. One tool for faecal source tracking is the analysis of faecal sterols which are present in faeces of animals in a range of distinctive ratios. Published ratios are able to discriminate between human and herbivore mammal faecal inputs but are of less value for identifying pollution from wildfowl, which can be a common cause of elevated bacterial indicators in rivers and streams. In this study, the sterol profiles of 50 avian-derived faecal specimens (seagulls, ducks and chickens) were examined alongside those of 57 ruminant faeces and previously published sterol profiles of human wastewater, chicken effluent and animal meatwork effluent. Two novel sterol ratios were identified as specific to avian faecal scats, which, when incorporated into a decision tree with human and herbivore mammal indicative ratios, were able to identify sterols from avian-polluted waterways. For samples where the sterol profile was not consistent with herbivore mammal or human pollution, avian pollution is indicated when the ratio of 24-ethylcholestanol/(24-ethylcholestanol + 24-ethylcoprostanol + 24-ethylepicoprostanol) is ≥0.4 (avian ratio 1) and the ratio of cholestanol/(cholestanol + coprostanol + epicoprostanol) is ≥0.5 (avian ratio 2). When avian pollution is indicated, further confirmation by targeted PCR specific markers can be employed if greater confidence in the pollution source is required. A 66% concordance between sterol ratios and current avian PCR markers was achieved when 56 water samples from polluted waterways were analysed.

  20. Structural insights into inhibition of Lipid I production in bacterial cell wall synthesis

    PubMed Central

    Tanino, Tetsuya; Kim, Mijung; Matsuda, Akira; Hong, Jiyong; Ichikawa, Satoshi; Lee, Seok-Yong

    2016-01-01

    Summary Antibiotic-resistant bacterial infection is a serious threat to public health. Peptidoglycan biosynthesis is a well-established target for antibiotic development. MraY (phospho-MurNAc-pentapeptide translocase) catalyzes the first and an essential membrane step of peptidoglycan biosynthesis. It is considered a very promising target for the development of new antibiotics, as many naturally occuring nucleoside inhibitors with antibacterial activity target this enzyme1-4. However, antibiotics targeting MraY have not been developed for clinical use mainly due to a lack of structural insight into inhibition of this enzyme. Here we present the crystal structure of MraY from Aquifex aeolicus (MraYAA) in complex with its naturally occurring inhibitor, muraymycin D2 (MD2). Upon binding MD2, MraYAA undergoes remarkably large conformational rearrangements near the active site, which lead to the formation of a nucleoside-binding pocket and a peptide-binding site. MD2 binds the nucleoside-binding pocket like a two-pronged plug inserting into a socket. Additional interactions it makes in the adjacent peptide-binding site anchor MD2 to and enhance its affinity for MraYAA. Surprisingly, MD2 does not interact with three acidic residues or the Mg2+ cofactor required for catalysis, suggesting that MD2 binds to MraYAA in a manner that overlaps with, but is distinct from its natural substrate, UDP-MurNAc-pentapeptide. We have deciphered the chemical logic of MD2 binding to MraYAA, including how it avoids the need for pyrophosphate and sugar moieties, which are essential features for substrate binding. The conformational plasticity of MraY could be the reason that it is the target of many structurally distinct inhibitors. These findings can inform the design of new inhibitors targeting MraY as well as its paralogs, WecA and TarO. PMID:27088606

  1. Role of a disordered steroid metabolome in the elucidation of sterol and steroid biosynthesis.

    PubMed

    Shackleton, Cedric H L

    2012-01-01

    In 1937 Butler and Marrian found large amounts of the steroid pregnanetriol in urine from a patient with the adrenogenital syndrome, a virilizing condition known to be caused by compromised adrenal secretion even in this pre-cortisol era. This introduced the concept of the study of altered excretion of metabolites as an in vivo tool for understanding sterol and steroid biosynthesis. This approach is still viable and has experienced renewed significance as the field of metabolomics. From the first cyclized sterol lanosterol to the most downstream product estradiol, there are probably greater than 30 steps. Based on a distinctive metabolome clinical disorders have now been attributed to about seven post-squalene cholesterol (C) biosynthetic steps and around 15 en-route to steroid hormones or needed for further metabolism of such hormones. Forty years ago it was widely perceived that the principal steroid biosynthetic defects were known but interest rekindled as novel metabolomes were documented. In his career this investigator has been involved in the study of many steroid disorders, the two most recent being P450 oxidoreductase deficiency and apparent cortisone reductase deficiency. These are of interest as they are due not to mutations in the primary catalytic enzymes of steroidogenesis but in ancillary enzymes needed for co-factor oxido-reduction A third focus of this researcher is Smith-Lemli-Opitz syndrome (SLOS), a cholesterol synthesis disorder caused by 7-dehydrocholesterol reductase mutations. The late George Schroepfer, in whose honor this article has been written, contributed greatly to defining the sterol metabolome of this condition. Defining the cause of clinically severe disorders can lead to improved treatment options. We are now involved in murine gene therapy studies for SLOS which, if successful could in the future offer an alternative therapy for this severe condition.

  2. Sterols indicate water quality and wastewater treatment efficiency.

    PubMed

    Reichwaldt, Elke S; Ho, Wei Y; Zhou, Wenxu; Ghadouani, Anas

    2017-01-01

    As the world's population continues to grow, water pollution is presenting one of the biggest challenges worldwide. More wastewater is being generated and the demand for clean water is increasing. To ensure the safety and health of humans and the environment, highly efficient wastewater treatment systems, and a reliable assessment of water quality and pollutants are required. The advance of holistic approaches to water quality management and the increasing use of ecological water treatment technologies, such as constructed wetlands and waste stabilisation ponds (WSPs), challenge the appropriateness of commonly used water quality indicators. Instead, additional indicators, which are direct measures of the processes involved in the stabilisation of human waste, have to be established to provide an in-depth understanding of system performance. In this study we identified the sterol composition of wastewater treated in WSPs and assessed the suitability of human sterol levels as a bioindicator of treatment efficiency of wastewater in WSPs. As treatment progressed in WSPs, the relative abundance of human faecal sterols, such as coprostanol, epicoprostanol, 24-ethylcoprostanol, and sitostanol decreased significantly and the sterol composition in wastewater changed significantly. Furthermore, sterol levels were found to be correlated with commonly used wastewater quality indicators, such as BOD, TSS and E. coli. Three of the seven sterol ratios that have previously been used to track sewage pollution in the environment, detected a faecal signal in the effluent of WSPs, however, the others were influenced by high prevalence of sterols originating from algal and fungal activities. This finding poses a concern for environmental assessment studies, because environmental pollution from waste stabilisation ponds can go unnoticed. In conclusion, faecal sterols and their ratios can be used as reliable indicators of treatment efficiency and water quality during wastewater

  3. Effects of seaweed sterols fucosterol and desmosterol on lipid membranes.

    PubMed

    Mouritsen, Ole G; Bagatolli, Luis A; Duelund, Lars; Garvik, Olav; Ipsen, John H; Simonsen, Adam Cohen

    2017-03-30

    Higher sterols are universally present in large amounts (20-30%) in the plasma membranes of all eukaryotes whereas they are universally absent in prokaryotes. It is remarkable that each kingdom of the eukaryotes has chosen, during the course of evolution, its preferred sterol: cholesterol in animals, ergosterol in fungi and yeast, phytosterols in higher plants, and e.g., fucosterol and desmosterol in algae. The question arises as to which specific properties do sterols impart to membranes and to which extent do these properties differ among the different sterols. Using a range of biophysical techniques, including calorimetry, fluorescence microscopy, vesicle-fluctuation analysis, and atomic force microscopy, we have found that fucosterol and desmosterol, found in red and brown macroalgae (seaweeds), similar to cholesterol support liquid-ordered membrane phases and induce coexistence between liquid-ordered and liquid-disordered domains in lipid bilayers. Fucosterol and desmosterol induce acyl-chain order in liquid membranes, but less effectively than cholesterol and ergosterol in the order: cholesterol>ergosterol>desmosterol>fucosterol, possibly reflecting the different molecular structure of the sterols at the hydrocarbon tail.

  4. New Marine Sterols from a Gorgonian Pinnigorgia sp.

    PubMed

    Chang, Yu-Chia; Hwang, Tsong-Long; Chao, Chih-Hua; Sung, Ping-Jyun

    2017-03-03

    Continuous chemical investigation of the gorgonian coral Pinnigorgia sp. resulted in the isolation of two new sterols, 5α,6α-epoxy-(22E,24R)-3β,11-dihydroxy-9,11-secoergosta-7-en-9-one (1) and (22R)-acetoxy-(24ξ)-ergosta-5-en-3β,25-diol (2). The structures of sterols 1 and 2 were elucidated using spectroscopic methods. Sterol 1 displayed inhibitory effects on the generation of superoxide anions and the release of elastase by human neutrophils with IC50 values of 8.65 and 5.86 μM, respectively. The structure of a known metabolite, pubinernoid A (3), is revised as (+)-loliolide (4).

  5. Comparative seasonal sterol profiles in edible parts of Mediterranean fish and shellfish species.

    PubMed

    Ozyurt, Gülsün; Kuley, Esmeray; Etyemez, Miray; Ozoğul, Fatih

    2013-06-01

    The effect of different seasons on sterol content of seafoods was investigated. There were four sterols (cholesterol, sitosterol, desmosterol and stigmasterol) identified, with cholesterol being the predominant sterol. Stigmasterol was a minor component in fish muscle, whilst sitosterol was one of the main phytosterols found in fish muscle. Cholesterol content of fish consisted of 38-100% of total sterols in fish and 54-80% of total sterols in shellfish. The highest cholesterol content of fish muscle was found in summer and the lowest in autumn, whereas season did not have any effect on cholesterol level of green tiger prawn and speckled shrimp. Total sterol content of fish muscle ranged from 49 to 110 mg/100 g, although the range of total sterols in shrimp muscle was between 62 and 91 mg/100 g. The result of the study showed that total sterols in fish were generally found at lower levels in winter compared with other seasons.

  6. A data mining approach to dinoflagellate clustering according to sterol composition: Correlations with evolutionary history.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study examined the sterol compositions of 102 dinoflagellates (including several previously unexamined species) using clustering techniques as a means of determining the relatedness of the organisms. In addition, dinoflagellate sterol-based relationships were compared statistically to dinoflag...

  7. Sterol and genomic analyses validate the sponge biomarker hypothesis

    PubMed Central

    Gold, David A.; Grabenstatter, Jonathan; de Mendoza, Alex; Riesgo, Ana; Ruiz-Trillo, Iñaki

    2016-01-01

    Molecular fossils (or biomarkers) are key to unraveling the deep history of eukaryotes, especially in the absence of traditional fossils. In this regard, the sterane 24-isopropylcholestane has been proposed as a molecular fossil for sponges, and could represent the oldest evidence for animal life. The sterane is found in rocks ∼650–540 million y old, and its sterol precursor (24-isopropylcholesterol, or 24-ipc) is synthesized today by certain sea sponges. However, 24-ipc is also produced in trace amounts by distantly related pelagophyte algae, whereas only a few close relatives of sponges have been assayed for sterols. In this study, we analyzed the sterol and gene repertoires of four taxa (Salpingoeca rosetta, Capsaspora owczarzaki, Sphaeroforma arctica, and Creolimax fragrantissima), which collectively represent the major living animal outgroups. We discovered that all four taxa lack C30 sterols, including 24-ipc. By building phylogenetic trees for key enzymes in 24-ipc biosynthesis, we identified a candidate gene (carbon-24/28 sterol methyltransferase, or SMT) responsible for 24-ipc production. Our results suggest that pelagophytes and sponges independently evolved C30 sterol biosynthesis through clade-specific SMT duplications. Using a molecular clock approach, we demonstrate that the relevant sponge SMT duplication event overlapped with the appearance of 24-isopropylcholestanes in the Neoproterozoic, but that the algal SMT duplication event occurred later in the Phanerozoic. Subsequently, pelagophyte algae and their relatives are an unlikely alternative to sponges as a source of Neoproterozoic 24-isopropylcholestanes, consistent with growing evidence that sponges evolved long before the Cambrian explosion ∼542 million y ago. PMID:26903629

  8. Sterol and genomic analyses validate the sponge biomarker hypothesis.

    PubMed

    Gold, David A; Grabenstatter, Jonathan; de Mendoza, Alex; Riesgo, Ana; Ruiz-Trillo, Iñaki; Summons, Roger E

    2016-03-08

    Molecular fossils (or biomarkers) are key to unraveling the deep history of eukaryotes, especially in the absence of traditional fossils. In this regard, the sterane 24-isopropylcholestane has been proposed as a molecular fossil for sponges, and could represent the oldest evidence for animal life. The sterane is found in rocks ∼650-540 million y old, and its sterol precursor (24-isopropylcholesterol, or 24-ipc) is synthesized today by certain sea sponges. However, 24-ipc is also produced in trace amounts by distantly related pelagophyte algae, whereas only a few close relatives of sponges have been assayed for sterols. In this study, we analyzed the sterol and gene repertoires of four taxa (Salpingoeca rosetta, Capsaspora owczarzaki, Sphaeroforma arctica, and Creolimax fragrantissima), which collectively represent the major living animal outgroups. We discovered that all four taxa lack C30 sterols, including 24-ipc. By building phylogenetic trees for key enzymes in 24-ipc biosynthesis, we identified a candidate gene (carbon-24/28 sterol methyltransferase, or SMT) responsible for 24-ipc production. Our results suggest that pelagophytes and sponges independently evolved C30 sterol biosynthesis through clade-specific SMT duplications. Using a molecular clock approach, we demonstrate that the relevant sponge SMT duplication event overlapped with the appearance of 24-isopropylcholestanes in the Neoproterozoic, but that the algal SMT duplication event occurred later in the Phanerozoic. Subsequently, pelagophyte algae and their relatives are an unlikely alternative to sponges as a source of Neoproterozoic 24-isopropylcholestanes, consistent with growing evidence that sponges evolved long before the Cambrian explosion ∼542 million y ago.

  9. Effects of terconazole and other azole antifungal agents on the sterol and carbohydrate composition of Candida albicans.

    PubMed

    Pfaller, M A; Riley, J; Koerner, T

    1990-01-01

    The effects of terconazole, a triazole antifungal, on the sterol and carbohydrate composition of Candida albicans was compared with that of three imidazoles: clotrimazole, miconazole, and butoconazole. Exposure of C. albicans to terconazole resulted in a profound depletion of ergosterol with a corresponding increase in lanosterol content versus control cells. Carbohydrate analysis revealed a significant (245%) increase in chitin and a minimal effect on glucan and mannan in terconazole-treated cells. Similar effects on sterol and carbohydrate composition were observed with clotrimazole and miconazole. Butoconazole had a similar effect on sterol composition but had no effect on carbohydrate composition. The decreased ergosterol and increased lanosterol content is consistent with 14 alpha-demethylase inhibition by terconazole and the other azoles. The increase in cell wall chitin is most likely due to deregulation of chitin synthesis secondary to ergosterol depletion in the cell membrane. Because both chitin and ergosterol are critical components of the fungal cell, perturbation of the production and localization of these components by terconazole is likely to contribute to the selective toxicity of this compound for C. albicans and other fungi.

  10. Sterol Biosynthesis Pathway as Target for Anti-trypanosomatid Drugs

    PubMed Central

    de Souza, Wanderley; Rodrigues, Juliany Cola Fernandes

    2009-01-01

    Sterols are constituents of the cellular membranes that are essential for their normal structure and function. In mammalian cells, cholesterol is the main sterol found in the various membranes. However, other sterols predominate in eukaryotic microorganisms such as fungi and protozoa. It is now well established that an important metabolic pathway in fungi and in members of the Trypanosomatidae family is one that produces a special class of sterols, including ergosterol, and other 24-methyl sterols, which are required for parasitic growth and viability, but are absent from mammalian host cells. Currently, there are several drugs that interfere with sterol biosynthesis (SB) that are in use to treat diseases such as high cholesterol in humans and fungal infections. In this review, we analyze the effects of drugs such as (a) statins, which act on the mevalonate pathway by inhibiting HMG-CoA reductase, (b) bisphosphonates, which interfere with the isoprenoid pathway in the step catalyzed by farnesyl diphosphate synthase, (c) zaragozic acids and quinuclidines, inhibitors of squalene synthase (SQS), which catalyzes the first committed step in sterol biosynthesis, (d) allylamines, inhibitors of squalene epoxidase, (e) azoles, which inhibit C14α-demethylase, and (f) azasterols, which inhibit Δ24(25)-sterol methyltransferase (SMT). Inhibition of this last step appears to have high selectivity for fungi and trypanosomatids, since this enzyme is not found in mammalian cells. We review here the IC50 values of these various inhibitors, their effects on the growth of trypanosomatids (both in axenic cultures and in cell cultures), and their effects on protozoan structural organization (as evaluted by light and electron microscopy) and lipid composition. The results show that the mitochondrial membrane as well as the membrane lining the protozoan cell body and flagellum are the main targets. Probably as a consequence of these primary effects, other important changes take place in

  11. Inhibitory effects of various oxygenated sterols on the differentiation and function of tumor-specific cytotoxic T lymphocytes

    SciTech Connect

    Spangrude, G.J.; Sherris, D.; Daynes, R.A.

    1982-05-01

    Irradiation of skin with ultraviolet light (UVL) is capable of causing many biological and biochemical changes in this complex organ. One early consequence is the oxidation of epidermal plasma membrane cholesterol, causing the induction of a wide variety of photoproducts. It is well recognized that some oxygenated sterols possess potent biological activity on mammalian cells by their ability to inhibit endogeneous mevalonate and cholesterol biosynthesis. In the few immunological systems that have been studied, there is general agreement that lymphocyte function is altered in the presence of certain oxygenated sterols. Insight into the biochemical basis for altered lymphocyte function is lacking, as both afferent and efferent blockades have been suggested. These studies were undertaken to determine the effect of various oxygenated sterols (representing a number of known cholesterol-derived photoproducts) on the generation (afferent) and function (efferent) of cytotoxic T lymphocytes (CTLs). Cell-mediated immune responses which result in the generation of both alloantigen-specific and syngeneic tumor-specific CTLs were evaluated. (JMT)

  12. Simultaneous effects of light intensity and phosphorus supply on the sterol content of phytoplankton.

    PubMed

    Piepho, Maike; Martin-Creuzburg, Dominik; Wacker, Alexander

    2010-12-31

    Sterol profiles of microalgae and their change with environmental conditions are of great interest in ecological food web research and taxonomic studies alike. Here, we investigated effects of light intensity and phosphorus supply on the sterol content of phytoplankton and assessed potential interactive effects of these important environmental factors on the sterol composition of algae. We identified sterol contents of four common phytoplankton genera, Scenedesmus, Chlamydomonas, Cryptomonas and Cyclotella, and analysed the change in sterol content with varying light intensities in both a high-phosphorus and a low-phosphorus approach. Sterol contents increased significantly with increasing light in three out of four species. Phosphorus-limitation reversed the change of sterol content with light intensity, i.e., sterol content decreased with increasing light at low phosphorus supply. Generally sterol contents were lower in low-phosphorus cultures. In conclusion, both light and phosphorus conditions strongly affect the sterol composition of algae and hence should be considered in ecological and taxonomic studies investigating the biochemical composition of algae. Data suggest a possible sterol limitation of growth and reproduction of herbivorous crustacean zooplankton during summer when high light intensities and low phosphorus supply decrease sterol contents of algae.

  13. The physiology of sterol nutrition in the pea aphid Acyrthosiphon pisum.

    PubMed

    Bouvaine, Sophie; T Behmer, Spencer; Lin, George G; Faure, Marie-Line; Grebenok, Robert J; Douglas, Angela E

    2012-11-01

    The phloem sap of fava bean (Vicia faba) plants utilized by the pea aphid Acyrthosiphon pisum contains three sterols, cholesterol, stigmasterol and sitosterol, in a 2:2:1 ratio. To investigate the nutritional value of these sterols, pea aphids were reared on chemically-defined diets containing each sterol at 0.1, 1 and 10μgml(-1) with a sterol-free diet as control. Larval growth rate and aphid lifespan did not vary significantly across the diets, indicating that sterol reserves can buffer some performance indices against a shortfall in dietary sterol over at least one generation. However, lifetime reproductive output was depressed in aphids on diets containing stigmasterol or no sterol, relative to diets supplemented with cholesterol or sitosterol. The cholesterol density of embryos in teneral adults was significantly higher than in the total body; and the number and biomass of embryos in aphids on diets with stigmasterol and no sterols were reduced relative to diets with cholesterol or sitosterol, indicating that the reproductive output of the pea aphid can be limited by the amount and composition of dietary sterol. In a complementary RNA-seq analysis of pea aphids reared on plants and diets with different sterol contents, 7.6% of the 17,417 detected gene transcripts were differentially expressed. Transcript abundance of genes with annotated function in sterol utilization did not vary significantly among treatments, suggesting that the metabolic response to dietary sterol may be mediated primarily at the level of enzyme function or metabolite concentration.

  14. Plant sterol metabolism. Δ(7)-Sterol-C5-desaturase (STE1/DWARF7), Δ(5,7)-sterol-Δ(7)-reductase (DWARF5) and Δ(24)-sterol-Δ(24)-reductase (DIMINUTO/DWARF1) show multiple subcellular localizations in Arabidopsis thaliana (Heynh) L.

    PubMed

    Silvestro, Daniele; Andersen, Tonni Grube; Schaller, Hubert; Jensen, Poul Erik

    2013-01-01

    Sterols are crucial lipid components that regulate membrane permeability and fluidity and are the precursors of bioactive steroids. The plant sterols exist as three major forms, free sterols, steryl glycosides and steryl esters. The storage of steryl esters in lipid droplets has been shown to contribute to cellular sterol homeostasis. To further document cellular aspects of sterol biosynthesis in plants, we addressed the question of the subcellular localization of the enzymes implicated in the final steps of the post-squalene biosynthetic pathway. In order to create a clear localization map of steroidogenic enzymes in cells, the coding regions of Δ(7)-sterol-C(5)-desaturase (STE1/DWARF7), Δ(24)-sterol-Δ(24)-reductase (DIMINUTO/DWARF1) and Δ(5,7)-sterol-Δ(7)-reductase (DWARF5) were fused to the yellow fluorescent protein (YFP) and transformed into Arabidopsis thaliana mutant lines deficient in the corresponding enzymes. All fusion proteins were found to localize in the endoplasmic reticulum in functionally complemented plants. The results show that both Δ(5,7)-sterol-Δ(7)-reductase and Δ(24)-sterol-Δ(24)-reductase are in addition localized to the plasma membrane, whereas Δ(7)-sterol-C(5)-desaturase was clearly detected in lipid particles. These findings raise new challenging questions about the spatial and dynamic cellular organization of sterol biosynthesis in plants.

  15. LM cell growth and membrane lipid adaptation to sterol structure.

    PubMed

    Rujanavech, C; Silbert, D F

    1986-06-05

    Using a sterol auxotroph of the LM cell mouse fibroblast, we demonstrate that relatively few cholesterol analogues can substitute for cholesterol as a growth factor. The auxotroph grows normally on desmosterol and trans-22-dehydrocholesterol and at reduced rates on dihydrocholesterol, campesterol, and 22,23-dihydrobrassicasterol. It does not grow with beta-sitosterol, stigmasterol, ergosterol, or cis-22-dehydrocholesterol when the sterol is present as sole supplement but does grow at normal rates when the analogue is supplied with suboptimal amounts of cholesterol. Two contrasting types of membrane lipid changes are observed in cells grown on cholesterol analogues. In cells grown with dihydrocholesterol, a marked increase in desaturation and elongation of fatty acids is noted. Conversely, when cells are grown with cis-22-dehydrocholesterol, desaturation and elongation of fatty acids are severely curtailed. Cells grown on alkyl sterols respond like cells grown on cis-22-dehydrocholesterol but in a less pronounced fashion. The effects of sterol substitution in mammalian cells versus in lower eukaryotes are compared, and an explanation for the secondary changes in fatty acid composition in terms of phospholipid phase behavior is suggested.

  16. Insect molting hormone and sterol biosynthesis in spinach

    SciTech Connect

    Grebenok, R.J.; Adler, J.H. )

    1990-05-01

    Insect molting hormones, which are produced by plants and are effective molecules in the control of insect crop pests, are biosynthesized in developing spinach leaves (Spinacia oleracea L.). The major sterols biosynthesized by spinach are avenasterol (24{alpha}-ethyl-5{alpha}-cholesta-7,24(28)-dien-3{beta}-ol), spinasterol (24{alpha}-ethyl-5{alpha}-cholesta-7,22-dien-3{beta}-ol), and 22-dihydrospinasterol (24{alpha}-ethyl-5{alpha}-cholest-7-en-3{beta}-ol). The major ecdysteroids biosynthesized are ecdysterone (2{beta},3{beta},14{alpha},20R,22R,25-hexahydroxy-5{beta}-cholest-7-en-6-one) and polypodine B (2{beta},3{beta},5{beta},14{alpha},20R,22R,25-heptahycroxycholest-7-en-6-one) and polypodine B (2{beta},3{beta},5{beta},14{alpha},20R,22R,25-heptahydroxycholest-7-en-6-one). When labeled 2-{sup 14}C-mevalonic acid was incorporated into young leaves isolated squalene, sterols and ecdysteroids contained the label. During a short (16 h) incorporation period in intact young leaves of 100 day old plants, the avenasterol has the highest specific activity in counts per minute per {mu}g of sterol followed by 22-dihydrospinasterol which is more highly labeled than spinasterol. The ecdysteroids synthesized, on an entire plant basis, account for 20% of the total steroid (sterol and ecdysteroid) isolated from the plant.

  17. Sterols and squalene in apricot (Prunus armeniaca L.) kernel oils: the variety as a key factor.

    PubMed

    Rudzińska, Magdalena; Górnaś, Paweł; Raczyk, Marianna; Soliven, Arianne

    2017-01-01

    The profile of sterols and squalene content in oils recovered from the kernels of 15 apricot (Prunus armeniaca L.) varieties were investigated. Nine sterols (campesterol, β-sitosterol, Δ5-avenasterol, 24-methylene-cycloartanol, cholesterol, gramisterol, Δ7-stigmasterol, Δ7-avenasterol and citrostadienol) were identified in apricot kernel oils. The β-sitosterol was the predominant sterol in each cultivar and consisted of 76-86% of the total detected sterols. The content of total sterols and squalene were significantly affected by the variety and ranged between 215.7-973.6 and 12.6-43.9 mg/100 g of oil, respectively.

  18. Occurrence of squalene and sterols in Cellulomonas dehydrogenans (Arnaudi 1942) comb. nov. Hester 1971.

    PubMed Central

    Weeks, O B; Francesconi, M D

    1978-01-01

    The neutral lipid fraction of the photochromogenic, coryneform bacterium Cellulomonas dehydrogenans (Arnaudi 1942) comb. nov. contains the sterol precursor squalene and at least two sterols, cholesterol and beta-sitosterol. The compounds were characterized by mass spectrometry and combination gas-liquid chromatography--mass spectrometry. De novo sterol biosynthetic ability was shown from incorporation of 14C from D-[U-14C]glucose into squalene and the sterol fraction. The squalene concentration approximated 0.002 to 0.005% of the total dry cell weight, and the sterols approximated 0.03 to 0.05%. Images PMID:101527

  19. Insight into methanol synthesis from CO2 hydrogenation on Cu(111): Complex reaction network and the effects of H2O

    SciTech Connect

    Zhao, Yafan; Yang, Yong; Mims, Charles A.; Peden, Charles HF; Li, Jun; Mei, Donghai

    2011-05-31

    Methanol synthesis from CO2 hydrogenation on supported Cu catalysts is of considerable importance in the chemical and energy industries. Although extensive experimental and theoretical efforts have been carried out in the past decades, the most fundamental questions such as the reaction mechanisms and the key reaction intermediates are still in debate. In the present work, a comprehensive reaction network for CO2 hydrogenation to methanol on Cu(111) was studied using periodic density functional theory (DFT) calculations. All of the elementary reaction steps in the reaction network were identified in an unbiased way with the dimer method. Our calculation results show that methanol synthesis from direct hydrogenation of formate on Cu(111) is not feasible due to the high activation barriers for some of the elementary steps. Instead, we find that CO2 hydrogenation to hydrocarboxyl (trans-COOH) is kinetically more favorable than formate in the presence of H2O via a unique proton transfer mechanism. The trans-COOH is then converted into hydroxymethylidyne (COH) via dihydroxycarbene (COHOH) intermediates, followed by three consecutive hydrogenation steps to form hydroxymethylene (HCOH), hydroxymethyl (H2COH), and methanol. This is consistent with recent experimental observations [1], which indicate that direct hydrogenation of formate will not produce methanol under dry hydrogen conditions. Thus, both experiment and computational modeling clearly demonstrate the important role of trace amounts of water in methanol synthesis from CO2 hydrogenation on Cu catalysts. The proposed methanol synthesis route on Cu(111) not only provides new insights into methanol synthesis chemistry, but also demonstrates again that spectroscopically observed surface species are often not critical reaction intermediates but rather spectator species. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  20. Suppressing Farnesyl Diphosphate Synthase Alters Chloroplast Development and Triggers Sterol-Dependent Induction of Jasmonate- and Fe-Related Responses1[OPEN

    PubMed Central

    Andrade, Paola; Caudepón, Daniel; Arró, Montserrat

    2016-01-01

    Farnesyl diphosphate synthase (FPS) catalyzes the synthesis of farnesyl diphosphate from isopentenyl diphosphate and dimethylallyl diphosphate. Arabidopsis (Arabidopsis thaliana) contains two genes (FPS1 and FPS2) encoding FPS. Single fps1 and fps2 knockout mutants are phenotypically indistinguishable from wild-type plants, while fps1/fps2 double mutants are embryo lethal. To assess the effect of FPS down-regulation at postembryonic developmental stages, we generated Arabidopsis conditional knockdown mutants expressing artificial microRNAs devised to simultaneously silence both FPS genes. Induction of silencing from germination rapidly caused chlorosis and a strong developmental phenotype that led to seedling lethality. However, silencing of FPS after seed germination resulted in a slight developmental delay only, although leaves and cotyledons continued to show chlorosis and altered chloroplasts. Metabolomic analyses also revealed drastic changes in the profile of sterols, ubiquinones, and plastidial isoprenoids. RNA sequencing and reverse transcription-quantitative polymerase chain reaction transcriptomic analysis showed that a reduction in FPS activity levels triggers the misregulation of genes involved in biotic and abiotic stress responses, the most prominent one being the rapid induction of a set of genes related to the jasmonic acid pathway. Down-regulation of FPS also triggered an iron-deficiency transcriptional response that is consistent with the iron-deficient phenotype observed in FPS-silenced plants. The specific inhibition of the sterol biosynthesis pathway by chemical and genetic blockage mimicked these transcriptional responses, indicating that sterol depletion is the primary cause of the observed alterations. Our results highlight the importance of sterol homeostasis for normal chloroplast development and function and reveal important clues about how isoprenoid and sterol metabolism is integrated within plant physiology and development. PMID

  1. Tracing origins of sewage and organic matter using dissolved sterols in Masan and Haengam Bay, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Hyo Jin; Hong, Sang Hee; Kim, Moonkoo; Ha, Sung Yong; An, Soon Mo; Shim, Won Joon

    2011-06-01

    Masan and Haengam Bays in Korea are highly polluted and semi-enclosed. Domestic and industrial effluents are directly or indirectly discharged into the bays through sewage treatment plants (STP) and creeks. In this study, 15 dissolved sterol compounds were determined in order to understand their sources and relative contribution. Freshwater samples were taken from 13 creeks and at two STP sites on a monthly basis. Total dissolved sterol concentrations ranged from 993 to 4158 ng/L. The concentrations of sterols in winter were higher than in summer. Among the sterols analyzed, cholesterol, β-sitosterol, coprostanol and cholestanone were major compounds in creek water. Seawater samples were concurrently collected at 21 stations in Masan Bay. Total sterol concentrations ranged 118-6,956 ng/L. Inner bay showed high concentrations of sterols in summer, while outer bay showed high sterol concentrations in winter. Among the sterols, cholesterol, β-sitosterol and brassicasterol were major compounds in seawater. In order to examine the contribution of urban sewage, the concentration of coprostanol and fecal sterol ratios were calculated. Most of the creek water, inner bay and near STP outlet samples were affected by sewage. Terrestrial organic matters accounted for a high proportion of dissolved organic matter origin. Fecal origins were relatively high in the inner bay areas and in the STP outlet, while sterols of marine origin were high in the outer bay areas.

  2. Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane.

    PubMed

    Iaea, David B; Mao, Shu; Lund, Frederik W; Maxfield, Frederick R

    2017-02-16

    Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and non-vesicular sterol transport processes. Using the fluorescent cholesterol analog, dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t1/2 of 12-15 minutes. Approximately 70% of sterol transport is ATP-independent and, therefore, non-vesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. We found that a soluble sterol transport protein, STARD4, accounts for ∼25% of total sterol transport and ∼33% of non-vesicular sterol transport between the plasma membrane and ERC. This study shows that non-vesicular sterol transport mechanisms, and STARD4 in particular, account for a large fraction of sterol transport between the plasma membrane and the ERC.

  3. Fragility of plasma membranes in Saccharomyces cerevisiae enriched with different sterols.

    PubMed Central

    Hossack, J A; Rose, A H

    1976-01-01

    Saccharomyces cerevisiae NCYC 366, grown under strictly anaerobic conditions to induce requirements for an unsaturated fatty acid (supplied by Tween 80) and a sterol, contained free sterol fractions enriched to the extent of 67 to 93% with the exogenously supplied sterol (campesterol, cholesterol, 7-dehydrocholesterol, 22, 23-dihydrobrassicasterol, beta-sitosterol, or stigmasterol). Cells enriched in any one of the sterols did not differ in volume, growth rate, contents of free sterol, esters and phospholipids, or phospholipid composition. Cholesterol-enriched cells contained about 2% more lipid than cells enriched in any of the other sterols, which was largely accounted for by increased contents of triacylglycerols and, to a lesser extent, esterified sterols. Phospholipids were enriched to the extent of about 52 to 63% with C18:1 residues. Cells enriched in ergosterol or stigmasterol were slightly less susceptible to the action of a wall-digesting basidiomycete glucanase than cells enriched with any one of the other sterols. The capacity of the plasma membrane to resist stretching, as indicated by the stability and volume of spheroplasts suspended in hypotonic solutions of buffered sorbitol (particularly in the range 0.9 to 0.7 M), was greater with spheroplasts enriched in sterols with an unsaturated side chain at C17 (ergosterol or stigmasterol) than with any of the other sterols. Plasma membranes were obtained from spheroplasts enriched in cholesterol or stigmasterol and had free sterol fractions containing 70 and 71%, respectively, of the sterol supplied exogenously to the cells. The sterol-phospholipid molar ratios in these membranes were, respectively, 1:7 and 1:8. PMID:776948

  4. Two families of sterol methyltransferases are involved in the first and the second methylation steps of plant sterol biosynthesis.

    PubMed

    Bouvier-Navé, P; Husselstein, T; Benveniste, P

    1998-08-15

    Two methyl transfers are involved in the biosynthesis of 24-methyl and 24-ethyl sterols, which play major roles in plant growth and development. The first methyl transfer applies to cycloartenol, the second to 24-methylene lophenol. About ten cDNA clones encoding S-adenosyl-L-methionine (AdoMet) sterol methyltransferases (SMTs) have been isolated so far from various plants. According to their deduced amino acid sequences, they were classified in two families, smtl and smt2; in addition, smt2 cDNAs were shown to encode a 24-methylene lophenol C24 methyltransferase [Bouvier-Navé, P., Husselstein, T., Desprez, T. & Benveniste, P. (1997) Eur. J. Biochem. 246, 518-529]. We now report the comparison of two cDNAs isolated from Nicotiana tabacum, Ntsmt1-1 which belongs to the first SMT cDNA family and Ntsmt2-1 which belongs to the second. Both cDNAs were expressed in the yeast null mutant erg6, deficient in SMT. Whereas erg6 is devoid of 24-alkyl sterols, erg6 Ntsmt1-1 contained a majority of 24-methylene sterols and erg6 Ntsmt2-1, a majority of 24-ethylidene sterols, indicating distinct functions for the expression products of these cDNAs. In the presence of AdoMet, delipidated microsomes from erg6 Ntsm1-1 efficiently converted cycloartenol into 24-methylene cycloartanol, but did not produce any 24-ethylidene lophenol upon incubation with 24-methylene lophenol. This demonstrates that cDNA Ntsmt1-1 (and most probably the other plant SMT cDNAs of the first family) encode(s) a cycloartenol C24 methyltransferase. In contrast, delipidated microsomes of erg6 Ntsmt2-1 were shown to methylate preferentially 24-methylene lophenol, as expected from an SMT encoded by an smt2 cDNA. In summary, among various cDNAs isolated from N. tabacum, one (Ntsmt1-1) belongs to the first family of plant SMT cDNAs according to its deduced amino acid sequence and was shown to encode a cycloartenol C24 methyltransferase, whereas another (Ntsmt2-1) belongs to the second family and was shown to encode

  5. [Sterol extracts from Begonia Sinensis Rhizome against respiratory inflammation].

    PubMed

    Yao, Yong; Jiang, Wei; Li, Yu-shan

    2015-08-01

    The acute and chronic respiratory tract inflammation models were made to investigate the effect and mechanism of sterol extracts from Begonia Sinensis Rhizome (BSR). The first model of acute lung injury was made with Kunming mice by inhaling cigarette smoke, then the mice were treated with different concentrations of BSR sterol extracts. Lung tissue morphology was detected by HE staining, TNF-alpha/MPO were detected by Elisa, and cPLA2 protein were, detected by Western blotting respectively. Results showed that in model group, lung sheet became real, alveolar space shrank or disappeared, alveolar septum was thickened, plenty of inflammatory cells were infiltrated, capillary blood vessels were congestive and the expression of TNF-α, MPO, cPLA2 increased; after administration, a small amount of inflammatory cells were infiltrated, alveolar septum became obvious, capillary congestion status was significantly relieved and the expression of TNF-α, MPO, cPLA2 decreased (P < 0.05). The second model of chronic respiratory tract inflammation in BALB/c mice with bronchial asthma was induced by OVA, then the mice were treated with different concentrations of BSR sterol extracts. Lung tissue morphology was detected by HE staining, indexes such as IL-4, IL-5, IL-13 were detected by Elisa, and the cPLA2 protein expression was detected by Western blotting respectively. Results showed that in model group, a lot of inflammatory cells around lung vessels and bronchi exuded, bronchial goblet cells proliferated and the expression of IL-4, IL-5, IL-13, cPLA2 increased; after administration, inflammatory and goblet cell hyperplasia reduced, the expression of IL-4, IL-5, IL-13, cPLA2 also decreased (P < 0.05). The above results showed BSR sterol extracts could resist against respiratory inflammation by inhibiting cPLA2 in a dose-dependent manner.

  6. A lanostane triterpenoid and three cholestane sterols from Tilia kiusiana.

    PubMed

    Shimada, Marie; Ozawa, Masaaki; Iwamoto, Kojiro; Fukuyama, Yoshiyasu; Kishida, Akio; Ohsaki, Ayumi

    2014-01-01

    Kiusianins A-D (1-4) were isolated from the leaves of a Japanese endemic plant, Tilia kiusiana, together with 14 known compounds. The structures of a new lanostane-type triterpenoid 1 and three new cholestane-type sterols 2-4 were elucidated by spectroscopic methods, including two dimensional (2D) NMR. All the compounds isolated were evaluated for their cytotoxicity against two human cancer cell lines, HeLa and HL-60.

  7. Sterol-Rich Membrane Domains Define Fission Yeast Cell Polarity.

    PubMed

    Makushok, Tatyana; Alves, Paulo; Huisman, Stephen Michiel; Kijowski, Adam Rafal; Brunner, Damian

    2016-05-19

    Cell polarization is crucial for the functioning of all organisms. The cytoskeleton is central to the process but its role in symmetry breaking is poorly understood. We study cell polarization when fission yeast cells exit starvation. We show that the basis of polarity generation is de novo sterol biosynthesis, cell surface delivery of sterols, and their recruitment to the cell poles. This involves four phases occurring independent of the polarity factor cdc42p. Initially, multiple, randomly distributed sterol-rich membrane (SRM) domains form at the plasma membrane, independent of the cytoskeleton and cell growth. These domains provide platforms on which the growth and polarity machinery assembles. SRM domains are then polarized by the microtubule-dependent polarity factor tea1p, which prepares for monopolar growth initiation and later switching to bipolar growth. SRM polarization requires F-actin but not the F-actin organizing polarity factors for3p and bud6p. We conclude that SRMs are key to cell polarization.

  8. Distribution of free and glycosylated sterols within Cycas micronesica plants.

    PubMed

    Marler, Thomas E; Shaw, Christopher A

    2010-02-02

    Flour derived from Cycas micronesica seeds was once the dominant source of starch for Guam's residents. Cycad consumption has been linked to high incidence of human neurodegenerative diseases. We determined the distribution of the sterols stigmasterol and β-sitosterol and their derived glucosides stigmasterol β-d-glucoside and β-sitosterol β-d-glucoside among various plant parts because they have been identified in cycad flour and have been shown to elicit neurodegenerative outcomes. All four compounds were common in seeds, sporophylls, pollen, leaves, stems, and roots. Roots contained the greatest concentration of both free sterols, and photosynthetic leaflet tissue contained the greatest concentration of both steryl glucosides. Concentration within the three stem tissue categories was low compared to other organs. Reproductive sporophyll tissue contained free sterols similar to seeds, but greater concentration of steryl glucosides than seeds. One of the glucosides was absent from pollen. Concentration in young seeds was higher than old seeds as reported earlier, but concentration did not differ among age categories of leaf, sporophyll, or vascular tissue. The profile differences among the various tissues within these organs may help clarify the physiological role of these compounds.

  9. Attenuation of Leishmania infantum chagasi Metacyclic Promastigotes by Sterol Depletion

    PubMed Central

    Gaur Dixit, Upasna; Barker, Jason H.; Teesch, Lynn M.; Love-Homan, Laurie; Donelson, John E.; Wilson, Mary E.

    2013-01-01

    The infectious metacyclic promastigotes of Leishmania protozoa establish infection in a mammalian host after they are deposited into the dermis by a sand fly vector. Several Leishmania virulence factors promote infection, including the glycosylphosphatidylinositol membrane-anchored major surface protease (MSP). Metacyclic Leishmania infantum chagasi promastigotes were treated with methyl-beta-cyclodextrin (MβCD), a sterol-chelating reagent, causing a 3-fold reduction in total cellular sterols as well as enhancing MSP release without affecting parasite viability in vitro. MβCD-treated promastigotes were more susceptible to complement-mediated lysis than untreated controls and reduced the parasite load 3-fold when inoculated into BALB/c mice. Paradoxically, MβCD-treated promastigotes caused a higher initial in vitro infection rate in human or murine macrophages than untreated controls, although their intracellular multiplication was hindered upon infection establishment. There was a corresponding larger amount of covalently bound C3b than iC3b on the parasite surfaces of MβCD-treated promastigotes exposed to healthy human serum in vitro, as well as loss of MSP, a protease that enhances C3b cleavage to iC3b. Mass spectrometry showed that MβCD promotes the release of proteins into the extracellular medium, including both MSP and MSP-like protein (MLP), from virulent metacyclic promastigotes. These data support the hypothesis that plasma membrane sterols are important for the virulence of Leishmania protozoa at least in part through retention of membrane virulence proteins. PMID:23630964

  10. Attenuation of Leishmania infantum chagasi metacyclic promastigotes by sterol depletion.

    PubMed

    Yao, Chaoqun; Gaur Dixit, Upasna; Barker, Jason H; Teesch, Lynn M; Love-Homan, Laurie; Donelson, John E; Wilson, Mary E

    2013-07-01

    The infectious metacyclic promastigotes of Leishmania protozoa establish infection in a mammalian host after they are deposited into the dermis by a sand fly vector. Several Leishmania virulence factors promote infection, including the glycosylphosphatidylinositol membrane-anchored major surface protease (MSP). Metacyclic Leishmania infantum chagasi promastigotes were treated with methyl-beta-cyclodextrin (MβCD), a sterol-chelating reagent, causing a 3-fold reduction in total cellular sterols as well as enhancing MSP release without affecting parasite viability in vitro. MβCD-treated promastigotes were more susceptible to complement-mediated lysis than untreated controls and reduced the parasite load 3-fold when inoculated into BALB/c mice. Paradoxically, MβCD-treated promastigotes caused a higher initial in vitro infection rate in human or murine macrophages than untreated controls, although their intracellular multiplication was hindered upon infection establishment. There was a corresponding larger amount of covalently bound C3b than iC3b on the parasite surfaces of MβCD-treated promastigotes exposed to healthy human serum in vitro, as well as loss of MSP, a protease that enhances C3b cleavage to iC3b. Mass spectrometry showed that MβCD promotes the release of proteins into the extracellular medium, including both MSP and MSP-like protein (MLP), from virulent metacyclic promastigotes. These data support the hypothesis that plasma membrane sterols are important for the virulence of Leishmania protozoa at least in part through retention of membrane virulence proteins.

  11. Dietary phosphilipids and sterols protective against peptic ulceration.

    PubMed

    Tovey, F I; Bardhan, K D; Hobsley, M

    2013-09-01

    The prevalence of duodenal ulceration in regions of developing countries with a stable diet is related to the staple food(s) in that diet. A higher prevalence occurs in areas where the diet is principally milled rice, refined wheat or maize, yams, cassava, sweet potato or green bananas, and a lower prevalence in areas where the staple diet is based on unrefined wheat or maize, soya, certain millets or certain pulses. Experiments using animal peptic ulcer models showed that the lipid fraction in foods from the staple diets of low prevalence areas gave protection against both gastric and duodenal ulceration, including ulceration due to non-steroidal anti-inflammatory drugs (NSAIDs), and also promoted healing of ulceration. The protective activity was found to lie in the phospholipid, sterol and sterol ester fractions of the lipid. Amongst individual phospholipids present in the phospholipid fraction, phosphatidyl ethanolamine (cephalin) and phosphatidyl choline (Lecithin) predominated. The sterol fraction showing activity contained β-sitosterol, stigmasterol and an unidentified isomer of β-sitosterol. The evidence shows that dietary phytosterols and phospholipids, both individually and in combination, have a protective effect on gastroduodenal mucosa. These findings may prove to be important in the prevention and management of duodenal and gastric ulceration including ulceration due to NSAIDs.

  12. Sterols of Saccharomyces cerevisiae erg6 Knockout Mutant Expressing the Pneumocystis carinii S-Adenosylmethionine:Sterol C-24 Methyltransferase (SAM:SMT)

    PubMed Central

    Kaneshiro, Edna S.; Johnston, Laura Q.; Nkinin, Stephenson W.; Romero, Becky I.; Giner, José-Luis

    2014-01-01

    The AIDS-associated lung pathogen Pneumocystis is classified as a fungus although Pneumocystis has several distinct features such as the absence of ergosterol, the major sterol of most fungi. The P. carinii S-adenosylmethionine:sterol C24-methyltransferase (SAM:SMT) enzyme, coded by the erg6 gene, transfers either one or two methyl groups to the C-24 position of the sterol side chain producing both C28 and C29 24-alkylsterols in approximately the same proportions whereas most fungal SAM:SMT transfer only one methyl group to the side chain. The sterol compositions of wild type Sacchromyces cerevisiae, the erg6 knockout mutant (Δerg6), and Δerg6 expressing the P. carinii or the S. cerevisiae erg6 gene were analyzed by a variety of chromatographic and spectroscopic procedures to examine functional complementation in the yeast expression system. Detailed sterol analyses were obtained using high performance liquid chromatography (HPLC) and proton nuclear magnetic resonance spectroscopy (1H-NMR). The P. carinii SAM:SMT in the Δerg6 restored its ability to produce the C28 sterol ergosterol as the major sterol, and also resulted in low levels of C29 sterols. This indicates that while the P. carinii SAM:SMT in the yeast Δerg6 cells was able to transfer a second methyl group to the side chain, the action of Δ24(28)-sterol reductase (coded by the erg4 gene) in the yeast cells prevented the formation and accumulation of as many C29 sterols as that found in P. carinii. PMID:25230683

  13. Absence of sterols constrains food quality of cyanobacteria for an invasive freshwater bivalve.

    PubMed

    Basen, Timo; Rothhaupt, Karl-Otto; Martin-Creuzburg, Dominik

    2012-09-01

    The accumulation of cyanobacterial biomass may severely affect the performance of aquatic consumers. Here, we investigated the role of sterols in determining the food quality of cyanobacteria for the invasive clam Corbicula fluminea, which has become a common benthic invertebrate in many freshwater ecosystems throughout the world. In standardized growth experiments, juvenile clams were fed mixtures of different cyanobacteria (Anabaena variabilis, Aphanothece clathrata, Synechococcus elongatus) or sterol-containing eukaryotic algae (Cryptomonas sp., Nannochloropsis limnetica, Scenedesmus obliquus). In addition, the cyanobacterial food was supplemented with different sterols. We provide evidence that somatic growth of C. fluminea on cyanobacterial diets is constrained by the absence of sterols, as indicated by a growth-enhancing effect of sterol supplementation. Thus, our findings contribute to our understanding of the consequences of cyanobacterial mass developments for benthic consumers and highlight the importance of considering sterols as potentially limiting nutrients in aquatic food webs.

  14. Sterol O-Acyltransferase 2-Driven Cholesterol Esterification Opposes Liver X Receptor-Stimulated Fecal Neutral Sterol Loss.

    PubMed

    Warrier, Manya; Zhang, Jun; Bura, Kanwardeep; Kelley, Kathryn; Wilson, Martha D; Rudel, Lawrence L; Brown, J Mark

    2016-02-01

    Statin drugs have proven a successful and relatively safe therapy for the treatment of atherosclerotic cardiovascular disease (CVD). However, even with the substantial low-density lipoprotein (LDL) cholesterol lowering achieved with statin treatment, CVD remains the top cause of death in developed countries. Selective inhibitors of the cholesterol esterifying enzyme sterol-O acyltransferase 2 (SOAT2) hold great promise as effective CVD therapeutics. In mouse models, previous work has demonstrated that either antisense oligonucleotide (ASO) or small molecule inhibitors of SOAT2 can effectively reduce CVD progression, and even promote regression of established CVD. Although it is well known that SOAT2-driven cholesterol esterification can alter both the packaging and retention of atherogenic apoB-containing lipoproteins, here we set out to determine whether SOAT2-driven cholesterol esterification can also impact basal and liver X receptor (LXR)-stimulated fecal neutral sterol loss. These studies demonstrate that SOAT2 is a negative regulator of LXR-stimulated fecal neutral sterol loss in mice.

  15. Sterol O-Acyltransferase 2-Driven Cholesterol Esterification Opposes Liver X Receptor-Stimulated Fecal Neutral Sterol Loss

    PubMed Central

    Warrier, Manya; Zhang, Jun; Bura, Kanwardeep; Kelley, Kathryn; Wilson, Martha D.; Rudel, Lawrence L.; Brown, J. Mark

    2016-01-01

    Statin drugs have proven a successful and relatively safe therapy for the treatment of atherosclerotic cardiovascular disease (CVD). However, even with the substantial low-density lipoprotein (LDL) cholesterol lowering achieved with statin treatment, CVD remains the top cause of death in developed countries. Selective inhibitors of the cholesterol esterifying enzyme sterol-O acyltransferase 2 (SOAT2) hold great promise as effective CVD therapeutics. In mouse models, previous work has demonstrated that either antisense oligonucleotide (ASO) or small molecule inhibitors of SOAT2 can effectively reduce CVD progression, and even promote regression of established CVD. Although it is well known that SOAT2-driven cholesterol esterification can alter both the packaging and retention of atherogenic apoB-containing lipoproteins, here we set out to determine whether SOAT2-driven cholesterol esterification can also impact basal and liver X receptor (LXR)-stimulated fecal neutral sterol loss. These studies demonstrate that SOAT2 is a negative regulator of LXR-stimulated fecal neutral sterol loss in mice. PMID:26729489

  16. Mechanistic Insight into a Sugar-Accelerated Tin-Catalyzed Cascade Synthesis of α-Hydroxy-γ-butyrolactone from Formaldehyde.

    PubMed

    Yamaguchi, Sho; Matsuo, Takeaki; Motokura, Ken; Sakamoto, Yasuharu; Miyaji, Akimitsu; Baba, Toshihide

    2015-11-01

    Applications of the formose reaction, which involves the formation of sugars from formaldehyde, have previously been confined to the selective synthesis of unprotected sugars. Herein, it is demonstrated that α-hydroxy-γ-butyrolactone (HBL), which is one of the most important intermediates in pharmaceutical syntheses, can be produced from paraformaldehyde. In the developed reaction system, homogeneous tin chloride exhibits high catalytic activity and the addition of mono- and disaccharides accelerates the formation of HBL. These observations suggest that the formose reaction may serve as a feasible pathway for the synthesis of important chemicals.

  17. A mathematical model of the sterol regulatory element binding protein 2 cholesterol biosynthesis pathway.

    PubMed

    Bhattacharya, Bonhi S; Sweby, Peter K; Minihane, Anne-Marie; Jackson, Kim G; Tindall, Marcus J

    2014-05-21

    Cholesterol is one of the key constituents for maintaining the cellular membrane and thus the integrity of the cell itself. In contrast high levels of cholesterol in the blood are known to be a major risk factor in the development of cardiovascular disease. We formulate a deterministic nonlinear ordinary differential equation model of the sterol regulatory element binding protein 2 (SREBP-2) cholesterol genetic regulatory pathway in a hepatocyte. The mathematical model includes a description of genetic transcription by SREBP-2 which is subsequently translated to mRNA leading to the formation of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), a main regulator of cholesterol synthesis. Cholesterol synthesis subsequently leads to the regulation of SREBP-2 via a negative feedback formulation. Parameterised with data from the literature, the model is used to understand how SREBP-2 transcription and regulation affects cellular cholesterol concentration. Model stability analysis shows that the only positive steady-state of the system exhibits purely oscillatory, damped oscillatory or monotic behaviour under certain parameter conditions. In light of our findings we postulate how cholesterol homeostasis is maintained within the cell and the advantages of our model formulation are discussed with respect to other models of genetic regulation within the literature.

  18. A mathematical model of the sterol regulatory element binding protein 2 cholesterol biosynthesis pathway

    PubMed Central

    Bhattacharya, Bonhi S.; Sweby, Peter K.; Minihane, Anne-Marie; Jackson, Kim G.; Tindall, Marcus J.

    2014-01-01

    Cholesterol is one of the key constituents for maintaining the cellular membrane and thus the integrity of the cell itself. In contrast high levels of cholesterol in the blood are known to be a major risk factor in the development of cardiovascular disease. We formulate a deterministic nonlinear ordinary differential equation model of the sterol regulatory element binding protein 2 (SREBP-2) cholesterol genetic regulatory pathway in a hepatocyte. The mathematical model includes a description of genetic transcription by SREBP-2 which is subsequently translated to mRNA leading to the formation of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), a main regulator of cholesterol synthesis. Cholesterol synthesis subsequently leads to the regulation of SREBP-2 via a negative feedback formulation. Parameterised with data from the literature, the model is used to understand how SREBP-2 transcription and regulation affects cellular cholesterol concentration. Model stability analysis shows that the only positive steady-state of the system exhibits purely oscillatory, damped oscillatory or monotic behaviour under certain parameter conditions. In light of our findings we postulate how cholesterol homeostasis is maintained within the cell and the advantages of our model formulation are discussed with respect to other models of genetic regulation within the literature. PMID:24444765

  19. Factors affecting intestinal absorption of cholesterol and plant sterols and stanols.

    PubMed

    Ikeda, Ikuo

    2015-01-01

    Various factors affect intestinal absorption of cholesterol and plant sterols and stanols. Plant sterols and stanols are generally less absorptive than cholesterol. Differential absorption rates among various plant sterols and stanols have been also reported. Although it was suggested that differential absorption among cholesterol and various plant sterols was determined by difference in excretion rates of sterols and stanols through ATP-binding cassette transporter (ABC) G5/ABCG8 of intestinal cells, our study suggests that affinity for and solubility in bile salt micelles can be important determinants for differential absorption of plant sterols and stanols. It was also suggested that plant sterols were transiently incorporated into intestinal cells and then excreted to intestinal lumen through ABCG5/ABCG8. However, in a rat study, transient incorporation of sitosterol into intestinal cells was not observed, suggesting that sitosterol is differentiated from cholesterol at the incorporation site of intestinal cells. It is well established that plant sterols inhibit intestinal absorption of cholesterol and exert a hypocholesterolemic activity. Plant sterols are solubilized in bile salt micelles as cholesterol. Our study clearly showed that because the sterol-solubilizing capacity of bile salt micelles was limited, plant sterols solubilized in micelles reduced the solubility of cholesterol. This can be the major cause of inhibition of cholesterol absorption by plant sterols. Pancreatic cholesterol esterase accelerates intestinal absorption of unesterified cholesterol. Although it was suggested that cholesterol esterase accelerated esterification of cholesterol incorporated into intestinal cells and acted as a transporter at the surface of intestinal cells, our research revealed that the accelerated cholesterol absorption was caused by hydrolysis of phosphatidylcholine in bile salt micelles. It is thought that hydrolysis of phosphatidylcholine reduces the affinity of

  20. Bioactive sterols from marine resources and their potential benefits for human health.

    PubMed

    Kim, Se-Kwon; Van Ta, Quang

    2012-01-01

    Bioactive agents from marine resources have shown their valuable health beneficial effects. Therefore, increase knowledge on novel functional ingredients with biological activities from marine animal and microbe has gained much attention. Sterols are recognized as potential in development functional food ingredients and pharmaceutical agents. Marine resources, with a great diversity, can be a very interesting natural resource of sterols. This chapter focuses on biological activities of marine animal and microbe sterols with potential health beneficial applications in functional foods and pharmaceuticals.

  1. Increased plant sterol deposition in vascular tissue characterizes patients with severe aortic stenosis and concomitant coronary artery disease.

    PubMed

    Luister, Alexandra; Schött, Hans Frieder; Husche, Constanze; Schäfers, Hans-Joachim; Böhm, Michael; Plat, Jogchum; Gräber, Stefan; Lütjohann, Dieter; Laufs, Ulrich; Weingärtner, Oliver

    2015-07-01

    The aim of the study was to evaluate the relationship between phytosterols, oxyphytosterols, and other markers of cholesterol metabolism and concomitant coronary artery disease (CAD) in patients with severe aortic stenosis who were scheduled for elective aortic valve replacement. Markers of cholesterol metabolism (plant sterols and cholestanol as markers of cholesterol absorption and lathosterol as an indicator of cholesterol synthesis) and oxyphytosterols were determined in plasma and aortic valve tissue from 104 consecutive patients with severe aortic stenosis (n=68 statin treatment; n=36 no statin treatment) using gas chromatography-flame ionization and mass spectrometry. The extent of CAD was determined by coronary angiography prior to aortic valve replacement. Patients treated with statins were characterized by lower plasma cholesterol, cholestanol, and lathosterol concentrations. However, statin treatment did not affect the sterol concentrations in cardiovascular tissue. The ratio of campesterol-to-cholesterol was increased by 0.46±0.34μg/mg (26.0%) in plasma of patients with CAD. The absolute values for the cholesterol absorption markers sitosterol and campesterol were increased by 18.18±11.59ng/mg (38.8%) and 11.40±8.69ng/mg (30.4%) in the tissues from patients with documented CAD compared to those without concomitant CAD. Campesterol oxides were increased by 0.06±0.02ng/mg (17.1%) in the aortic valve cusps and oxidized sitosterol-to-cholesterol ratios were up-regulated by 0.35±0.2ng/mg (22.7%) in the plasma of patients with CAD. Of note, neither cholestanol nor the ratio of cholestanol-to-cholesterol was associated with CAD. Patients with concomitant CAD are characterized by increased deposition of plant sterols, but not cholestanol in aortic valve tissue. Moreover, patients with concomitant CAD were characterized by increased oxyphytosterol concentrations in plasma and aortic valve cusps.

  2. Nitrile-converting enzymes as a tool to improve biocatalysis in organic synthesis: recent insights and promises.

    PubMed

    Gong, Jin-Song; Shi, Jin-Song; Lu, Zhen-Ming; Li, Heng; Zhou, Zhe-Min; Xu, Zheng-Hong

    2017-02-01

    Nitrile-converting enzymes, including nitrilase and nitrile hydratase (NHase), have received increasing attention from researchers of industrial biocatalysis because of their critical role as a tool in organic synthesis of carboxylic acids and amides from nitriles. To date, these bioconversion approaches are considered as one of the most potential industrial processes using resting cells or purified enzymes as catalysts for production of food additives, pharmaceutical, and agrochemical precursors. This review focuses on the distribution and catalytic mechanism research of nitrile-converting enzymes in recent years. Molecular biology aspects to improve the biocatalytic performance of microbial nitrilase and NHase are demonstrated. The process developments of microbial nitrilase and NHase for organic synthesis are also discussed.

  3. New insights on the synthesis and electronic transport in bulk polycrystalline Pr-doped SrTiO{sub 3−δ}

    SciTech Connect

    Dehkordi, Arash Mehdizadeh; Bhattacharya, Sriparna; Darroudi, Taghi; Alshareef, Husam N.; Tritt, Terry M.

    2015-02-07

    Recently, we have reported a significant enhancement in the electronic and thermoelectric properties of bulk polycrystalline SrTiO{sub 3} ceramics via praseodymium doping. This improvement was originated from the simultaneous enhancement in the thermoelectric power factor and reduction in thermal conductivity, which was contributed to the non-uniform distribution of Pr dopants. In order to further understand the underlying mechanism, we herein investigate the role of praseodymium doping source (Pr{sub 2}O{sub 3} versus Pr{sub 6}O{sub 11}) on the synthesis and electronic transport in Pr-doped SrTiO{sub 3} ceramics. It was observed that the high-temperature electronic transport properties are independent of the choice of praseodymium doping source for samples prepared following our synthesis strategy. Theoretical calculations were also performed in order to estimate the maximum achievable power factor and the corresponding optimal carrier concentration. The result suggests the possibility of further improvement of the power factor. This study should shed some light on the superior electronic transport in bulk polycrystalline Pr-doped SrTiO{sub 3} ceramics and provide new insight on further improvement of the thermoelectric power factor.

  4. Impact of ice melting on distribution of particulate sterols in glacial fjords of Chilean Patagonia

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Marcelo H.; Riquelme, Pablo; Pantoja, Silvio

    2016-04-01

    We analyzed variability in abundance and composition of sterols in waters of the fjord adjacent to glacier Jorge Montt, one of the fastest retreated glaciers in Patagonian Icefields. The study was carried out between August 2012 and November 2013 under different meltwater scenarios. Distribution of sterols in surface and bottom waters was determined by Gas Chromatography coupled to Mass Spectrometry. Sterol concentration ranged from 18 to 1726 ng/L in surface and bottom waters and was positive correlated with chlorophyll-a concentration. Under high melting conditions in austral summer, surface meltwaters showed high concentrations of sterols and were dominated by methylene-cholesterol, a representative sterol of centric diatoms. In the area near open ocean and in austral autumn, winter and spring in proglacial fjord, lower sterol concentrations in surface waters were accompanied by other microalgae sterols and an increase in relative abundance of plant sterols, evidencing a different source of organic matter. In autumn, when high meltwater flux was also evidenced, presence of stanols and an uncommon tri-unsaturated sterol suggests influence of meltwaters in composition of sterols in the downstream fjord. We conclude that ice melting can modify sterol composition by setting conditions for development of a singular phytoplankton population able to thrive in surface meltwater and by carrying glacier organic matter into Patagonian glacial fjords. In projected ice melting scenario, these changes in organic matter quantity and quality can potentially affect availability of organic substrates for heterotrophic activity and trophic status of glacial fjords. This research was funded by COPAS Sur-Austral (PFB-31)

  5. Xanthohumol Improves Diet-induced Obesity and Fatty Liver by Suppressing Sterol Regulatory Element-binding Protein (SREBP) Activation.

    PubMed

    Miyata, Shingo; Inoue, Jun; Shimizu, Makoto; Sato, Ryuichiro

    2015-08-14

    Sterol regulatory element-binding proteins (SREBPs) are key transcription factors that stimulate the expression of genes involved in fatty acid and cholesterol biosynthesis. Here, we demonstrate that a prenylated flavonoid in hops, xanthohumol (XN), is a novel SREBP inactivator that reduces the de novo synthesis of fatty acid and cholesterol. XN independently suppressed the maturation of SREBPs of insulin-induced genes in a manner different from sterols. Our results suggest that XN impairs the endoplasmic reticulum-to-Golgi translocation of the SREBP cleavage-activating protein (SCAP)-SREBP complex by binding to Sec23/24 and blocking SCAP/SREBP incorporation into common coated protein II vesicles. Furthermore, in diet-induced obese mice, dietary XN suppressed SREBP-1 target gene expression in the liver accompanied by a reduction of the mature form of hepatic SREBP-1, and it inhibited the development of obesity and hepatic steatosis. Altogether, our data suggest that XN attenuates the function of SREBP-1 by repressing its maturation and that it has the potential of becoming a nutraceutical food or pharmacological agent for improving metabolic syndrome.

  6. Xanthohumol Improves Diet-induced Obesity and Fatty Liver by Suppressing Sterol Regulatory Element-binding Protein (SREBP) Activation*

    PubMed Central

    Miyata, Shingo; Inoue, Jun; Shimizu, Makoto; Sato, Ryuichiro

    2015-01-01

    Sterol regulatory element-binding proteins (SREBPs) are key transcription factors that stimulate the expression of genes involved in fatty acid and cholesterol biosynthesis. Here, we demonstrate that a prenylated flavonoid in hops, xanthohumol (XN), is a novel SREBP inactivator that reduces the de novo synthesis of fatty acid and cholesterol. XN independently suppressed the maturation of SREBPs of insulin-induced genes in a manner different from sterols. Our results suggest that XN impairs the endoplasmic reticulum-to-Golgi translocation of the SREBP cleavage-activating protein (SCAP)-SREBP complex by binding to Sec23/24 and blocking SCAP/SREBP incorporation into common coated protein II vesicles. Furthermore, in diet-induced obese mice, dietary XN suppressed SREBP-1 target gene expression in the liver accompanied by a reduction of the mature form of hepatic SREBP-1, and it inhibited the development of obesity and hepatic steatosis. Altogether, our data suggest that XN attenuates the function of SREBP-1 by repressing its maturation and that it has the potential of becoming a nutraceutical food or pharmacological agent for improving metabolic syndrome. PMID:26140926

  7. Effect of Sterol Structure on Chain Ordering of an Unsaturated Phospholipid: A 2H-NMR Study of POPC/Sterol Membranes

    NASA Astrophysics Data System (ADS)

    Shaghaghi, Mehran; Thewalt, Jenifer; Zuckermann, Martin

    2012-10-01

    The physical properties of biological membranes are considerably altered by the presence of sterols. In particular, sterols help to maintain the integrity of the cell by adjusting the fluidity of the plasma membrane. Cholesterol is in addition an important component of lipid rafts which are hypothesized to compartmentalize the cell membrane surface thereby making it possible for certain proteins to function. Using 2H-NMR spectroscopy, we studied the effect of a series of different sterols on the chain ordering of POPC, an unsaturated phospholipid present in eukaryotic cell membranes. We were able to assigned specific roles to the structural differences between the sterols by comparing the manner in which they affect the average lipid chain conformation of POPC.

  8. Transport of resistance-inducing sterols in phloem sap of barley.

    PubMed

    Lehrer, A T; Dugassa-Gobena, D; Vidal, S; Seifert, K

    2000-01-01

    After root application of [7alpha-3H]-7beta-hydroxysitosterol and [3alpha,6beta-3H2]-6alpha-hydroxylathosterol these sterols could be detected in the leaves and phloem sap feeding aphids. These results imply that the phloem sap is a sterol transport system in barley plants.

  9. Regulation of Sterol Biosynthesis in the Human Fungal Pathogen Aspergillus fumigatus: Opportunities for Therapeutic Development

    PubMed Central

    Dhingra, Sourabh; Cramer, Robert A.

    2017-01-01

    Sterols are a major component of eukaryotic cell membranes. For human fungal infections caused by the filamentous fungus Aspergillus fumigatus, antifungal drugs that target sterol biosynthesis and/or function remain the standard of care. Yet, an understanding of A. fumigatus sterol biosynthesis regulatory mechanisms remains an under developed therapeutic target. The critical role of sterol biosynthesis regulation and its interactions with clinically relevant azole drugs is highlighted by the basic helix loop helix (bHLH) class of transcription factors known as Sterol Regulatory Element Binding Proteins (SREBPs). SREBPs regulate transcription of key ergosterol biosynthesis genes in fungi including A. fumigatus. In addition, other emerging regulatory pathways and target genes involved in sterol biosynthesis and drug interactions provide additional opportunities including the unfolded protein response, iron responsive transcriptional networks, and chaperone proteins such as Hsp90. Thus, targeting molecular pathways critical for sterol biosynthesis regulation presents an opportunity to improve therapeutic options for the collection of diseases termed aspergillosis. This mini-review summarizes our current understanding of sterol biosynthesis regulation with a focus on mechanisms of transcriptional regulation by the SREBP family of transcription factors. PMID:28203225

  10. Processes of recovering fatty acids and sterols from tall oil pitch

    SciTech Connect

    Hughes, R. E.

    1985-06-18

    An improved process of enhancing the recovery of fatty acids from tall oil pitch is disclosed. The process includes a hydrolysis step for increasing the free fatty acid available for recovery from tall oil pitch during the distillation process. The hydrolysis step also enables the recovery of sterols where the tall oil pitch is of the type which is rich in sterol esters.

  11. Inhaled tobacco sterols: uptake by the lungs and disposition to selected organs of rats

    SciTech Connect

    Holden, W.E.; Maier, J.M.; Liebler, J.M.; Malinow, M.R.

    1988-08-01

    Tobacco sterols (cholesterol, beta-sitosterol, campesterol, and stigmasterol) are present in tobacco smoke and appear in plasma of mammals exposed to cigarette smoke. Because tobacco sterols may be important in the pathogenesis of smoking-induced lung and vascular diseases, we studied the pattern of deposition of cigarette sterols in the lungs and appearance of cigarette sterols in plasma and body organs of rats. After exposure to twenty 5 ml puffs of smoke from tobacco labeled with (4-/sup 14/C)cholesterol or beta-(4-/sup 14/C)sitosterol, rats were killed just after exposure (day 0) and on days 2, 5, 8, 11, 15, and 30, and the lungs and selected body organs analyzed for activity. We found that cigarette sterols are associated with particulates in cigarette smoke, deposited mostly in distal airspaces and parenchyma of the lungs, and appear in plasma and several body organs for more than 30 days after this single exposure to cigarette smoke. Bronchoalveolar lavage fluid contained relatively small amounts of radiolabel for only the first few days, suggesting that most of the sterols were rapidly incorporated in lung parenchyma. Because disorders of sterol metabolism have been implicated in a variety of diseases including atherosclerosis and cancer, the significance of tobacco sterols to human smoking-induced diseases deserves further study.

  12. A potential biochemical mechanism underlying the influence of sterol deprivation stress on Caenorhabditis elegans longevity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To investigate the biochemical mechanism for sterol-mediated alteration in aging in Caenorhabditis elegans, we established sterol depletion conditions by treating worms with azacoprostane, which reduced mean lifespan of adult C. elegans by 35%. Proteomic analyses of egg proteins from treated and un...

  13. Altered sterol profile induced in Leishmania amazonensis by a natural dihydroxymethoxylated chalcone

    PubMed Central

    Torres-Santos, Eduardo Caio; Sampaio-Santos, Maria Isabel; Buckner, Frederick S.; Yokoyama, Kohei; Gelb, Michael; Urbina, Julio A.; Rossi-Bergmann, Bartira

    2009-01-01

    Objectives The effects of the antileishmanial chalcone 2′,6′-dihydroxy-4′-methoxychalcone (DMC) on Leishmania amazonensis sterol composition and biosynthesis were investigated to obtain information about the mechanism of growth inhibition by DMC on this parasite. Methods The interference of sterol biosynthesis by DMC was studied in drug-treated promastigotes by two different methods. (i) Newly synthesized sterols from parasites grown in the presence of [3H]mevalonate were analysed by thin layer chromatography (TLC)/fluorography. (ii) Total sterols extracted from the parasites grown with or without DMC were characterized by gas chromatography coupled to mass spectroscopy (GC/MS). Results TLC and GC/MS analyses of sterols extracted from DMC-treated promastigotes revealed the accumulation of early precursors and a reduction in the levels of C-14 demethylated and C-24 alkylated sterols, as well as a reduction in exogenous cholesterol uptake. Conclusions This study demonstrates that the natural chalcone DMC alters the sterol composition of L. amazonensis and suggests that the parasite target is different from other known sterol inhibitors. PMID:19176591

  14. Effect of sterol esters on lipid composition and antioxidant status of erythrocyte membrane of hypercholesterolemic rats.

    PubMed

    Sengupta, Avery; Ghosh, Mahua

    2014-01-01

    Hypercholesterolemia is a major cause of coronary heart disease. Erythrocyte membrane is affected during hypercholesterolemia. The effect of EPA-DHA rich sterol ester and ALA rich sterol ester on erythrocyte membrane composition, osmotic fragility in normal and hypercholesterolemic rats and changes in antioxidant status of erythrocyte membrane were studied. Erythrocyte membrane composition, osmotic fragility of the membrane and antioxidant enzyme activities was analyzed. Osmotic fragility data suggested that the erythrocyte membrane of hypercholesterolemia was relatively more fragile than that of the normal rats' membrane which could be reversed with the addition of sterol esters in the diet. The increased plasma cholesterol in hypercholesterolemic rats could also be lowered by the sterol ester administration. There was also marked changes in the antioxidant enzyme activities of the erythrocyte membrane. Antioxidant enzyme levels decreased in the membrane of the hypercholesterolemic subjects were increased with the treatment of the sterol esters. The antioxidative activity of ALA rich sterol ester was better in comparison to EPA-DHA rich sterol ester. In conclusion, rat erythrocytes appear to be deformed and became more fragile in cholesterol rich blood. This deformity and fragility was partially reversed by sterol esters by virtue of their ability to lower the extent of hypercholesterolemia.

  15. Ultrasonic biodiesel synthesis from crude Jatropha curcas oil with heterogeneous base catalyst: mechanistic insight and statistical optimization.

    PubMed

    Choudhury, Hanif A; Goswami, Partha Pratim; Malani, Ritesh S; Moholkar, Vijayanand S

    2014-05-01

    This paper reports studies in ultrasound-assisted heterogeneous solid catalyzed (CaO) synthesis of biodiesel from crude Jatropha curcas oil. The synthesis has been carried out in two stages, viz. esterification and trans-esterification. The esterification process is not influenced by ultrasound. The transesterification process, however, shows marked enhancement with ultrasound. A statistical experimental design has been used to optimize the process conditions for the synthesis. XRD analysis confirms formation of Ca(OMe)2, which is the active catalyst for transesterification reaction. The optimum values of parameters for the highest yield of transesterification have been determined as follows: alcohol to oil molar ratio ≈ 11, catalyst concentration ≈ 5.5 wt.%, and temperature ≈ 64°C. The activation energy of the reaction is calculated as 133.5 kJ/mol. The heterogeneity of the system increases mass transfer constraints resulting in approx. 4 × increase in activation energy as compared to homogeneous alkali catalyzed system. It is also revealed that intense micro-convection induced by ultrasound enhances the mass transfer characteristics of the system with ∼ 20% reduction in activation energy, as compared to mechanically agitated systems. Influence of catalyst concentration and alcohol to oil molar ratio on the transesterification yield is inter-linked through formation of methoxy ions and their diffusion to the oil-alcohol interface, which in turn is determined by the volume fractions of the two phases in the reaction mixture. As a result, the highest transesterification yield is obtained at the moderate values of catalyst concentration and alcohol to oil molar ratio.

  16. Sterol 14alpha-demethylase activity in Streptomyces coelicolor A3(2) is associated with an unusual member of the CYP51 gene family.

    PubMed Central

    Lamb, David C; Fowler, Kay; Kieser, Tobias; Manning, Nigel; Podust, Larissa M; Waterman, Michael R; Kelly, Diane E; Kelly, Steven L

    2002-01-01

    The annotation of the genome sequence of Streptomyces coelicolor A3(2) revealed a cytochrome P450 (CYP) resembling various sterol 14alpha-demethylases (CYP51). The putative CYP open reading frame (SC7E4.20) was cloned with a tetrahistidine tag appended to the C-terminus and expressed in Escherichia coli. Protein purified to electrophoretic homogeneity was observed to bind the 14-methylated sterols lanosterol and 24-methylene-24,25-dihydrolanosterol (24-MDL). Reconstitution experiments with E. coli reductase partners confirmed activity in 14alpha-demethylation for 24-MDL, but not lanosterol. An S. coelicolor A3(2) mutant containing a transposon insertion in the CYP51 gene, which will abolish synthesis of the functional haemoprotein, was isolated as a viable strain, the first time a CYP51 has been identified as non-essential. The role of this CYP in bacteria is intriguing. No sterol product was detected in non-saponifiable cell extracts of the parent S. coelicolor A3(2) strain or of the mutant. S. coelicolor A3(2) CYP51 contains very few of the conserved CYP51 residues and, even though it can catalyse 14alpha-demethylation, it probably has another function in Streptomyces. We propose that it is a member of a new CYP51 subfamily. PMID:12023899

  17. Regulation of Sterol Content in Membranes by Subcellular Compartmentation of Steryl-Esters Accumulating in a Sterol-Overproducing Tobacco Mutant.

    PubMed Central

    Gondet, L.; Bronner, R.; Benveniste, P.

    1994-01-01

    The study of sterol overproduction in tissues of LAB 1-4 mutant tobacco (Nicotiana tabacum L. cv Xanthi) (P. Maillot-Vernier, H. Schaller, P. Benveniste, G. Belliard [1989] Biochem Biophys Res Commun 165: 125-130) over several generations showed that the overproduction phenotype is stable in calli, with a 10-fold stimulation of sterol content when compared with wild-type calli. However, leaves of LAB 1-4 plants obtained after two steps of self-fertilization were characterized by a mere 3-fold stimulation, whereas calli obtained from these plants retained a typical sterol-overproducing mutant phenotype (i.e. a 10-fold increase of sterol content). These results suggest that the expression of the LAB 1-4 phenotype is dependent on the differentiation state of cells. Most of the sterols accumulating in the mutant tissues were present as steryl-esters, which were minor species in wild-type tissues. Subcellular fractionation showed that in both mutant and wild-type tissues, free sterols were associated mainly with microsomal membranes. In contrast, the bulk of steryl-esters present in mutant tissues was found in the soluble fraction of cells. Numerous lipid droplets were detected in the hyaloplasm of LAB 1-4 cells by cytochemical and cytological techniques. After isolation, these lipid granules were shown to contain steryl-esters. These results show that the overproduced sterols of mutant tissues accumulate as steryl-esters in hyaloplasmic bodies. The esterification process thus allows regulation of the amount of free sterols in membranes by subcellular compartmentation. PMID:12232218

  18. Method Development for the Determination of Free and Esterified Sterols in Button Mushrooms (Agaricus bisporus).

    PubMed

    Hammann, Simon; Vetter, Walter

    2016-05-04

    Ergosterol is the major sterol in button mushrooms (Agaricus bisporus) and can occur as free alcohol or esterified with fatty acids (ergosteryl esters). In this study, gas chromatography with mass spectrometry in the selected ion monitoring mode (GC/MS-SIM) was used to determine ergosterol and ergosteryl esters as well as other sterols and steryl esters in button mushrooms. Different quality control measures were established and sample preparation procedures were compared to prevent the formation of artifacts and the degradation of ergosteryl esters. The final method was then used for the determination of ergosterol (443 ± 44 mg/100 g dry matter (d.m.)) and esterified ergosterol (12 ± 6 mg/100 g d.m.) in button mushroom samples (n = 4). While the free sterol fraction was vastly dominated by ergosterol (∼90% of five sterols in total), the steryl ester fraction was more diversified (nine sterols in total, ergosterol ∼55%) and consisted primarily of linoleic acid esters.

  19. Plant sterols and stanols as cholesterol-lowering ingredients in functional foods.

    PubMed

    Kamal-Eldin, Afaf; Moazzami, Ali

    2009-01-01

    This article reviews developments related to the use of plant sterols and stanols as cholesterol-lowering ingredients in foods and nutraceuticals preparations. Plant sterols and stanols are extracted from the deodorizer distillates of vegetable oil refining and from tall oil, a by-product of paper pulping industry. Plant sterols/stanols inhibit cholesterol absorption possibly by competitively inhibiting its incorporation into the mixed micelles in the small intestine although other mechanisms can not be excluded. Daily consumption of 1-2 grams of plant sterols or stanols was shown to cause 10-20% reduction in low-density lipoprotein cholesterol (LDL cholesterol). Combinations of plant sterols/stanols with certain lipid-lowering ingredients were shown to potentate their cholesterol-lowering effects and, in some cases, add triacylglycerol-lowering effects. In this article, patents based information is also discussed.

  20. hydra Mutants of Arabidopsis Are Defective in Sterol Profiles and Auxin and Ethylene Signaling

    PubMed Central

    Souter, Martin; Topping, Jennifer; Pullen, Margaret; Friml, Jiri; Palme, Klaus; Hackett, Rachel; Grierson, Don; Lindsey, Keith

    2002-01-01

    The hydra mutants of Arabidopsis are characterized by a pleiotropic phenotype that shows defective embryonic and seedling cell patterning, morphogenesis, and root growth. We demonstrate that the HYDRA1 gene encodes a Δ8-Δ7 sterol isomerase, whereas HYDRA2 encodes a sterol C14 reductase, previously identified as the FACKEL gene product. Seedlings mutant for each gene are similarly defective in the concentrations of the three major Arabidopsis sterols. Promoter::reporter gene analysis showed misexpression of the auxin-regulated DR5 and ACS1 promoters and of the epidermal cell file–specific GL2 promoter in the mutants. The mutants exhibit enhanced responses to auxin. The phenotypes can be rescued partially by inhibition of auxin and ethylene signaling but not by exogenous sterols or brassinosteroids. We propose a model in which correct sterol profiles are required for regulated auxin and ethylene signaling through effects on membrane function. PMID:12034894

  1. Interferon Control of the Sterol Metabolic Network: Bidirectional Molecular Circuitry-Mediating Host Protection

    PubMed Central

    Robertson, Kevin A.; Ghazal, Peter

    2016-01-01

    The sterol metabolic network is emerging center stage in inflammation and immunity. Historically, observational clinical studies show that hypocholesterolemia is a common side effect of interferon (IFN) treatment. More recently, comprehensive systems-wide investigations of the macrophage IFN response reveal a direct molecular link between cholesterol metabolism and infection. Upon infection, flux through the sterol metabolic network is acutely moderated by the IFN response at multiple regulatory levels. The precise mechanisms by which IFN regulates the mevalonate-sterol pathway—the spine of the network—are beginning to be unraveled. In this review, we discuss our current understanding of the multifactorial mechanisms by which IFN regulates the sterol pathway. We also consider bidirectional communications resulting in sterol metabolism regulation of immunity. Finally, we deliberate on how this fundamental interaction functions as an integral element of host protective responses to infection and harmful inflammation. PMID:28066443

  2. Effect of temperature on the synthesis of silver nanoparticles with polyethylene glycol: new insights into the reduction mechanism

    NASA Astrophysics Data System (ADS)

    Fleitas-Salazar, Noralvis; Silva-Campa, Erika; Pedroso-Santana, Seidy; Tanori, Judith; Pedroza-Montero, Martín R.; Riera, Raúl

    2017-03-01

    Polyethylene glycol (PEG) molecules act as a reducing and stabilizing agent in the formation of silver nanoparticles. PEG undergoes thermal oxidative degradation at temperatures over 70 °C in the presence of oxygen. Here, we studied how the temperature and an oxidizing atmosphere could affect the synthesis of silver nanoparticles with PEG. We tested different AgNO3 concentrations for nanoparticles syntheses using PEG of low molecular weight, at 60 and 100 °C. At the higher temperature, the reducing action of PEG increased and the effect of PEG/Ag+ ratio on nanoparticles aggregation changed. These results suggest that different synthesis mechanisms operate at 60 and 100 °C. Thus, at 60 °C the reduction of silver ions can occur through the oxidation of the hydroxyl groups of PEG, as has been previously reported. We propose that the thermal oxidative degradation of PEG at 100 °C increases the number of both, functional groups and molecules that can reduce silver ions and stabilize silver nanoparticles. This degradation process could explain the enhancement of PEG reducing action observed by other authors when they increase the reaction temperature or use a PEG of higher molecular weight

  3. 21 CFR 101.83 - Health claims: plant sterol/stanol esters and risk of coronary heart disease (CHD).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...,” except that if the sole source of the plant sterols or stanols is vegetable oil, the claim may use the term “vegetable oil sterol esters” or “vegetable oil stanol esters”; (E) The claim does not attribute... supplies ___grams of vegetable oil sterol esters. (ii) Diets low in saturated fat and cholesterol...

  4. 21 CFR 101.83 - Health claims: plant sterol/stanol esters and risk of coronary heart disease (CHD).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...,” except that if the sole source of the plant sterols or stanols is vegetable oil, the claim may use the term “vegetable oil sterol esters” or “vegetable oil stanol esters”; (E) The claim does not attribute... supplies ___grams of vegetable oil sterol esters. (ii) Diets low in saturated fat and cholesterol...

  5. 21 CFR 101.83 - Health claims: plant sterol/stanol esters and risk of coronary heart disease (CHD).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...,” except that if the sole source of the plant sterols or stanols is vegetable oil, the claim may use the term “vegetable oil sterol esters” or “vegetable oil stanol esters”; (E) The claim does not attribute... supplies ___grams of vegetable oil sterol esters. (ii) Diets low in saturated fat and cholesterol...

  6. 21 CFR 101.83 - Health claims: plant sterol/stanol esters and risk of coronary heart disease (CHD).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...,” except that if the sole source of the plant sterols or stanols is vegetable oil, the claim may use the term “vegetable oil sterol esters” or “vegetable oil stanol esters”; (E) The claim does not attribute... supplies ___grams of vegetable oil sterol esters. (ii) Diets low in saturated fat and cholesterol...

  7. Lipid dynamics in yeast under haem-induced unsaturated fatty acid and/or sterol depletion.

    PubMed Central

    Ferreira, Thierry; Régnacq, Matthieu; Alimardani, Parissa; Moreau-Vauzelle, Carole; Bergès, Thierry

    2004-01-01

    In the yeast Saccharomyces cerevisiae, UFA (unsaturated fatty acids) and ergosterol syntheses are aerobic processes that require haem. We took advantage of a strain affected in haem synthesis ( hem1 Delta) to starve specifically for one or the other of these essential lipids in order to examine the consequences on the overall lipid composition. Our results demonstrate that reserve lipids (i.e. triacylglycerols and steryl esters) are depleted independently of haem availability and that their UFA and sterol content is not crucial to sustain residual growth under lipid depletion. In parallel to UFA starvation, a net accumulation of SFA (saturated fatty acids) is observed as a consequence of haem biosynthesis preclusion. Interestingly, the excess SFA are not mainly stored within triacylglycerols and steryl esters but rather within specific phospholipid species, with a marked preference for PtdIns. This results in an increase in the cellular PtdIns content. However, neutral lipid homoeostasis is perturbed under haem starvation. The contribution of two lipid particle-associated proteins (namely Tgl1p and Dga1p) to this process is described. PMID:14640980

  8. Sterol carrier protein-2 localization in endoplasmic reticulum and role in phospholipid formation.

    PubMed

    Starodub, O; Jolly, C A; Atshaves, B P; Roths, J B; Murphy, E J; Kier, A B; Schroeder, F

    2000-10-01

    Although sterol carrier protein-2 (SCP-2; also called nonspecific lipid transfer protein) binds fatty acids and fatty acyl-CoAs, its role in fatty acid metabolism is not fully understood. L-cell fibroblasts stably expressing SCP-2 were used to resolve the relationship between SCP-2 intracellular location and fatty acid transacylation in the endoplasmic reticulum. Indirect immunofluorescence double labeling and laser scanning confocal microscopy detected SCP-2 in peroxisomes > endoplasmic reticulum > mitochondria > lysosomes. SCP-2 enhanced incorporation of exogenous [(3)H]oleic acid into phospholipids and triacylglycerols of overexpressing cells 1.6- and 2.5-fold, respectively, stimulated microsomal incorporation of [1-(14)C]oleoyl-CoA into phosphatidic acid in vitro 13-fold, and exhibited higher specificity for unsaturated versus saturated fatty acyl-CoA. SCP-2 enhanced the rate-limiting step in microsomal phosphatidic acid biosynthesis mediated by glycerol-3-phosphate acyltransferase. SCP-2 also enhanced microsomal acyl-chain remodeling of phosphatidylethanolamine up to fivefold and phosphatidylserine twofold, depending on the specific fatty acyl-CoA, but had no effect on other phospholipid classes. In summary, these results were consistent with a role for SCP-2 in phospholipid synthesis in the endoplasmic reticulum.

  9. The IDOL–UBE2D complex mediates sterol-dependent degradation of the LDL receptor

    PubMed Central

    Zhang, Li; Fairall, Louise; Goult, Benjamin T.; Calkin, Anna C.; Hong, Cynthia; Millard, Christopher J.; Tontonoz, Peter; Schwabe, John W.R.

    2011-01-01

    We previously identified the E3 ubiquitin ligase IDOL as a sterol-dependent regulator of the LDL receptor (LDLR). The molecular pathway underlying IDOL action, however, remains to be determined. Here we report the identification and biochemical and structural characterization of an E2–E3 ubiquitin ligase complex for LDLR degradation. We identified the UBE2D family (UBE2D1–4) as E2 partners for IDOL that support both autoubiquitination and IDOL-dependent ubiquitination of the LDLR in a cell-free system. NMR chemical shift mapping and a 2.1 Å crystal structure of the IDOL RING domain–UBE2D1 complex revealed key interactions between the dimeric IDOL protein and the E2 enzyme. Analysis of the IDOL–UBE2D1 interface also defined the stereochemical basis for the selectivity of IDOL for UBE2Ds over other E2 ligases. Structure-based mutations that inhibit IDOL dimerization or IDOL–UBE2D interaction block IDOL-dependent LDLR ubiquitination and degradation. Furthermore, expression of a dominant-negative UBE2D enzyme inhibits the ability of IDOL to degrade the LDLR in cells. These results identify the IDOL–UBE2D complex as an important determinant of LDLR activity, and provide insight into molecular mechanisms underlying the regulation of cholesterol uptake. PMID:21685362

  10. Fecal sterols, seasonal variability, and probable sources along the ring of cenotes, Yucatan, Mexico

    NASA Astrophysics Data System (ADS)

    Arcega-Cabrera, F.; Velázquez-Tavera, N.; Fargher, L.; Derrien, M.; Noreña-Barroso, E.

    2014-11-01

    Rapid development in Yucatan has had a dramatic impact on the environment, especially the water supply. Groundwater is the only source of water in Yucatan, since surface water is virtually absent due to the karstic nature of the soil. The ring of cenotes (RC) is a geological feature which functions as a source of water and as nodes in the underground river system that canalizes water towards the coast. Numerous productive and domestic activities take place around the RC in the absence of wastewater treatment or sewage systems. Consequently, a number of researchers have hypothesized that pollutants could migrate from the land surface to the underlying aquifer and, eventually, to the coast. Therefore, the present study investigates the relationship among sources of fecal sterols and their levels in cenotes, using the expected levels of fecal sterols obtained by a spatial analysis of the sources and a Pollution Source Index. Accordingly, expected levels are compared with the detected levels of fecal sterols in 5 areas around the RC. Regarding levels, observed during a sampling campaign carried out along the RC during September 2011 (rainy season) and May 2012 (dry season), varied from low to high concentrations of sterols (0.5-2396.42 μg g- 1) and fecal sterols (0.3-1690.18 μg g- 1). These concentrations showed no relationship between neighboring cenotes, where similar fecal sterol concentrations or gradients were expected. When comparing expected fecal sterols levels with the detected ones, only two of the five analyzed areas concur, suggesting that no clear relationship exists among sources and fecal sterols levels at the regional scale. Multivariate analysis showed that fecal sterols were associated with sterols and fine grain particulates during the rainy season, which suggests co-transport. During the dry season, fecal sterols associated with fine grain particulate and organic matter, which indicates a change to a deposition phenomenon. These findings indicate

  11. Mutations in UDP-Glucose:sterol glucosyltransferase in Arabidopsis cause transparent testa phenotype and suberization defect in seeds.

    PubMed

    DeBolt, Seth; Scheible, Wolf-Rüdiger; Schrick, Kathrin; Auer, Manfred; Beisson, Fred; Bischoff, Volker; Bouvier-Navé, Pierrette; Carroll, Andrew; Hematy, Kian; Li, Yonghua; Milne, Jennifer; Nair, Meera; Schaller, Hubert; Zemla, Marcin; Somerville, Chris

    2009-09-01

    In higher plants, the most abundant sterol derivatives are steryl glycosides (SGs) and acyl SGs. Arabidopsis (Arabidopsis thaliana) contains two genes, UGT80A2 and UGT80B1, that encode UDP-Glc:sterol glycosyltransferases, enzymes that catalyze the synthesis of SGs. Lines having mutations in UGT80A2, UGT80B1, or both UGT80A2 and UGT8B1 were identified and characterized. The ugt80A2 lines were viable and exhibited relatively minor effects on plant growth. Conversely, ugt80B1 mutants displayed an array of phenotypes that were pronounced in the embryo and seed. Most notable was the finding that ugt80B1 was allelic to transparent testa15 and displayed a transparent testa phenotype and a reduction in seed size. In addition to the role of UGT80B1 in the deposition of flavanoids, a loss of suberization of the seed was apparent in ugt80B1 by the lack of autofluorescence at the hilum region. Moreover, in ugt80B1, scanning and transmission electron microscopy reveals that the outer integument of the seed coat lost the electron-dense cuticle layer at its surface and displayed altered cell morphology. Gas chromatography coupled with mass spectrometry of lipid polyester monomers confirmed a drastic decrease in aliphatic suberin and cutin-like polymers that was associated with an inability to limit tetrazolium salt uptake. The findings suggest a membrane function for SGs and acyl SGs in trafficking of lipid polyester precursors. An ancillary observation was that cellulose biosynthesis was unaffected in the double mutant, inconsistent with a predicted role for SGs in priming cellulose synthesis.

  12. Juvenile Hormone Synthesis: “esterify then epoxidize” or “epoxidize then esterify”? Insights from the Structural Characterization of Juvenile Hormone Acid Methyltransferase

    PubMed Central

    Defelipe, L.A; Dolghih, E.; Roitberg, A.E.; Nouzova, M.; Mayoral, J.G; Noriega, F.G.; Turjanski, A.G.

    2011-01-01

    Juvenile hormones (JHs) play key roles in regulating metamorphosis and reproduction in insects. The last two steps of JH synthesis diverge depending on the insect order. In Lepidoptera, epoxidation by a P450 monooxygenase precedes esterification by a juvenile hormone acid methyltransferase (JHAMT). In Orthoptera, Dictyoptera, Coleoptera and Diptera epoxidation follows methylation. The aim of our study was to gain insight into the structural basis of JHAMT’s substrate recognition as a means to understand the divergence of these pathways. Homology modeling was used to build the structure of Aedes aegypti JHAMT. The substrate binding site was identified, as well as the residues that interact with the methyl donor (S-adenosylmethionine) and the carboxylic acid of the substrate methyl acceptors, farnesoic acid (FA) and juvenile hormone acid (JHA). To gain further insight we generated the structures of Anopheles gambiae, Bombyx mori, Drosophila melanogaster and Tribolium castaneum JHAMTs. The modeling results were compared with previous experimental studies using recombinant proteins, whole insects, corpora allata or tissue extracts. The computational study helps explain the selectivity towards the (10R)-JHA isomer and the reduced activity for palmitic and lauric acids. The analysis of our results supports the hypothesis that all insect JHAMTs are able to recognize both FA and JHA as substrates. Therefore, the order of the methylation/epoxidation reactions may be primarily imposed by the epoxidase’s substrate specificity. In Lepidoptera, epoxidase might have higher affinity than JHAMT for FA, so epoxidation precedes methylation, while in most other insects there is no epoxidation of FA, but esterification of FA to form MF, followed by epoxidation to JH III. PMID:21195763

  13. Inhibition of Sterol Biosynthesis Reduces Tombusvirus Replication in Yeast and Plants▿

    PubMed Central

    Sharma, Monika; Sasvari, Zsuzsanna; Nagy, Peter D.

    2010-01-01

    The replication of plus-strand RNA viruses depends on subcellular membranes. Recent genome-wide screens have revealed that the sterol biosynthesis genes ERG25 and ERG4 affected the replication of Tomato bushy stunt virus (TBSV) in a yeast model host. To further our understanding of the role of sterols in TBSV replication, we demonstrate that the downregulation of ERG25 or the inhibition of the activity of Erg25p with an inhibitor (6-amino-2-n-pentylthiobenzothiazole; APB) leads to a 3- to 5-fold reduction in TBSV replication in yeast. In addition, the sterol biosynthesis inhibitor lovastatin reduced TBSV replication by 4-fold, confirming the importance of sterols in viral replication. We also show reduced stability for the p92pol viral replication protein as well as a decrease in the in vitro activity of the tombusvirus replicase when isolated from APB-treated yeast. Moreover, APB treatment inhibits TBSV RNA accumulation in plant protoplasts and in Nicotiana benthamiana leaves. The inhibitory effect of APB on TBSV replication can be complemented by exogenous stigmasterol, the main plant sterol, suggesting that sterols are required for TBSV replication. The silencing of SMO1 and SMO2 genes, which are orthologs of ERG25, in N. benthamiana reduced TBSV RNA accumulation but had a lesser inhibitory effect on the unrelated Tobacco mosaic virus, suggesting that various viruses show different levels of dependence on sterol biosynthesis for their replication. PMID:20015981

  14. Lipid-lowering Activity of Natural and Semi-Synthetic Sterols and Stanols.

    PubMed

    Taha, Dhiaa A; Wasan, Ellen K; Wasan, Kishor M; Gershkovich, Pavel

    2015-01-01

    Consumption of plant sterols/ stanols has long been demonstrated to reduce plasma cholesterol levels. The objective of this review is to demonstrate the lipid-lowering activity and anti-atherogenic effects of natural and semi-synthetic plant sterols/ stanols based on evidence from cell-culture studies, animal studies and clinical trials. Additionally, this review highlights certain molecular mechanisms by which plant sterols/ stanols lower plasma cholesterol levels with a special emphasis on factors that affect the cholesterol-lowering activity of plant sterols/stanols. The crystalline nature and the poor oil solubility of these natural products could be important factors that limit their cholesterol-lowering efficiency. Several attempts have been made to improve the cholesterol-lowering activity by enhancing the bioavailability of crystalline sterols and stanols. Approaches involved reduction of the crystal size and/or esterification with fatty acids from vegetable or fish oils. However, the most promising approach in this context is the chemical modification of plant sterols /stanols into water soluble disodium ascorbyl phytostanyl phosphates analogue by esterification with ascorbic acid. This novel semi-synthetic stanol derivative has improved efficacy over natural plant sterols/ stanols and can provide additional benefits by combining the cholesterol-lowering properties of plant stanols with the antioxidant potential of ascorbic acid. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

  15. Effects of plant sterols and stanols on intestinal cholesterol metabolism: suggested mechanisms from past to present.

    PubMed

    De Smet, Els; Mensink, Ronald P; Plat, Jogchum

    2012-07-01

    Plant sterols and stanols are natural food ingredients found in plants. It was already shown in 1950 that they lower serum low-density lipoprotein cholesterol (LDL-C) concentrations. Meta-analysis has reported that a daily intake of 2.5 g plant sterols/stanols reduced serum LDL-C concentrations up to 10%. Despite many studies, the underlying mechanism remains to be elucidated. Therefore, the proposed mechanisms that have been presented over the past decades will be described and discussed in the context of the current knowledge. In the early days, it was suggested that plant sterols/stanols compete with intestinal cholesterol for incorporation into mixed micelles as well as into chylomicrons. Next, the focus shifted toward cellular processes. In particular, a role for sterol transporters localized in the membranes of enterocytes was suggested. All these processes ultimately lowered intestinal cholesterol absorption. More recently, the existence of a direct secretion of cholesterol from the circulation into the intestinal lumen was described. First results in animal studies suggested that plant sterols/stanols activate this pathway, which also explains the increased fecal neutral sterol content and as such could explain the cholesterol-lowering activity of plant sterols/stanols.

  16. Sterols and triterpenes in cell culture of Hyssopus officinalis L.

    PubMed

    Skrzypek, Zuzanna; Wysokińska, Halina

    2003-01-01

    Cell suspension cultures from hypocotyl-derived callus of Hyssopus officinalis were found to produce two sterols i. e. beta-sitosterol (1) and stigmasterol (2), as well as several known pentacyclic triterpenes with an oleanene and ursene skeleton. The triterpenes were identified as oleanolic acid (3), ursolic acid (4), 2alpha,3beta-dihydroxyolean-12-en-28-oic acid (5), 2alpha,3beta-dihydroxyurs-12-en-28-oic acid (6), 2alpha,3beta,24-trihydroxyolean-12-en-28-oic acid (7), and 2alpha,3beta,24-trihydroxyurs-12-en-28-oic acid (8). Compounds 5-8 were isolated as their acetates (6, 8) or bromolactone acetates (5, 7).

  17. Contributions of other sterols to the estimation of cholesterol.

    PubMed

    Munster, D J; Lever, M; Carrell, R W

    1976-04-15

    The responses of 5alpha-cholestan-3beta-ol, 5alpha-cholest-7-ene-3beta-ol and cholesta-5,7-dien-3beta-ol, normally found in human serum, were examined by: (1) the Liebermann-Burchard reaction, (2) the Zak (ferric chloride) reaction, (3) an enzymatic cholesterol method monitored by estimating the amount of hydrogen peroxide produced, (4) an enzymatic cholesterol method monitored by observing the change in absorbance at 240 nm, and (5) gas chromatography. The results show that none of these methods is specific for cholesterol; contributions from the sterols examined range from zero to more than 150% relative to cholesterol. For the first four methods contributions depend on the conditions under which each test is performed.

  18. Cell-free transfer of sterols by plant fractions

    SciTech Connect

    Morre, D.J.; Wilkinson, F.E.; Morre, D.M. ); Moreau, P. ); Sandelius, A.S. ); Penel, C.; Greppin, H. )

    1990-05-01

    Microsomes from etiolated hypocotyls of soybean or leaves of light-grown spinach radiolabeled in vivo with ({sup 3}H)acetate or in vitro with ({sup 3}H)squalene or ({sup 3}H)cholesterol as donor transferred radioactivity to unlabeled acceptor membranes immobilized on nitrocellulose. Most efficient transfer was with plasma membrane or tonoplast as the acceptor. The latter were highly purified by aqueous two-phase partition (plasma membrane) and preparative free-flow electrophoresis (tonoplast and plasma membrane). Plasma membrane- and tonoplast-free microsomes and purified mitochondria were less efficient acceptors. Sterol transfer was verified by thin-layer chromatography of extracted lipids. Transfer was time- and temperature-dependent, required ATP but was not promoted by cytosol. The nature of the donor (endoplasmic reticulum, Golgi apparatus or both) and of the transfer mechanism is under investigation.

  19. Reduction in cholesterol absorption is enhanced by stearate-enriched plant sterol esters in hamsters.

    PubMed

    Rasmussen, Heather E; Guderian, David M; Wray, Curtis A; Dussault, Patrick H; Schlegel, Vicki L; Carr, Timothy P

    2006-11-01

    Consumption of plant sterol esters reduces plasma LDL cholesterol concentration by inhibiting intestinal cholesterol absorption. Commercially available plant sterol esters are prepared by esterifying free sterols to fatty acids from edible plant oils such as canola, soybean, and sunflower. To determine the influence of the fatty acid moiety on cholesterol metabolism, plant sterol esters were made with fatty acids from soybean oil (SO), beef tallow (BT), or purified stearic acid (SA) and fed to male hamsters for 4 wk. A control group fed no plant sterol esters was also included. Hamsters fed BT and SA had significantly lower cholesterol absorption and decreased concentrations of plasma non-HDL cholesterol and liver esterified cholesterol, and significantly greater fecal sterol excretion than SO and control hamsters. Cholesterol absorption was lowest in hamsters fed SA (7.5%), whereas it was 72.9% in control hamsters. Cholesterol absorption was correlated with fecal sterol excretion (r = -0.72, P < 0.001), liver cholesterol concentration (r = 0.88, P < 0.001), and plasma non-HDL cholesterol concentration (r = 0.85, P < 0.001). A multiple regression model that included each sterol ester type vs. cholesterol absorption indicated that intake of steryl stearate was the only dietary component that contributed significantly to the model (R2 = -0.75, P < 0.001). Therefore, our results demonstrate that BT and SA are more effective than SO in reducing cholesterol absorption, liver cholesterol, and plasma non-HDL cholesterol concentration, suggesting that cardioprotective benefits can be achieved by consuming stearate-enriched plant sterol esters.

  20. Mechanistic Insights into Validoxylamine A 7'-Phosphate Synthesis by VldE Using the Structure of the Entire Product Complex

    SciTech Connect

    Cavalier, Michael C.; Yim, Young-Sun; Asamizu, Shumpei; Neau, David; Almabruk, Khaled H.; Mahmud, Taifo; Lee, Yong-Hwan

    2013-09-09

    The pseudo-glycosyltransferase VldE catalyzes non-glycosidic C-N coupling between an unsaturated cyclitol and a saturated aminocyclitol with the conservation of the stereochemical configuration of the substrates to form validoxylamine A 7'-phosphate, the biosynthetic precursor of the antibiotic validamycin A. To study the molecular basis of its mechanism, the three-dimensional structures of VldE from Streptomyces hygroscopicus subsp. limoneus was determined in apo form, in complex with GDP, in complex with GDP and validoxylamine A 7'-phosphate, and in complex with GDP and trehalose. The structure of VldE with the catalytic site in both an “open” and “closed” conformation is also described. With these structures, the preferred binding of the guanine moiety by VldE, rather than the uracil moiety as seen in OtsA could be explained. The elucidation of the VldE structure in complex with the entirety of its products provides insight into the internal return mechanism by which catalysis occurs with a net retention of the stereochemical configuration of the donated cyclitol.

  1. Gas chromatography-mass spectrometry study of sterols from Pinus elliotti tissues.

    NASA Technical Reports Server (NTRS)

    Laseter, J. L.; Evans, R.; Weete, J. D.; Walkinshaw, C. H.

    1973-01-01

    A comparative study of the sterol components of slash pine (Pinus elliotti) callus tissue cultures, seeds, and seedlings was carried out using GC-MS techniques. Cholesterol, desmosterol, campesterol, stigmasterol, sitosterol and cycloeucalenol were identified in all tissues while lophenol and 24-methylenelophenol were identified in only the seed and seedlings. 24-Ethylidenelophenol was detected in trace concentrations in only the seedlings. Sitosterol was the predominant sterol component, i.e., 80.8, 38.1 and 47.8% of the tissue culture, seed and seedling sterols, respectively.

  2. Sterol composition and phytosterol utilization and metabolism in the milkweed bug.

    PubMed

    Svoboda, J A; Dutky, S R; Robbins, W E; Kaplanis, J N

    1977-03-01

    Analysis of the sterols of the milkweed bug, Oncopeltus fasciatus (Dallas) and dietary sunflowerseeds revealed that there is little, if any, conversion of dietary C28 OR C29 phytosterols to cholesterol in this phytophagous insect. The dietary sterols are apparently utilized with little alteration both during development to the adult stage and egg production, and cholesterol comprises less than 1% of the sterols in either adult males and females or in the eggs. The significance of these findings are discussed in light of the recent discovery that the C28-ecdysone, makisterone A, is the predominant molting hormone inthe embryonated egg of the milkweed bug.

  3. Ionic Liquid Solvation versus Catalysis: Computational Insight from a Multisubstituted Imidazole Synthesis in [Et2NH2][HSO4

    PubMed Central

    Abbasov, Vagif; Ducati, Lucas C.; Talybov, Avtandil

    2016-01-01

    Abstract The mechanisms of a tetrasubstituted imidazole [2‐(2,4,5‐triphenyl‐1 H‐imidazol‐1‐yl)ethan‐1‐ol] synthesis from benzil, benzaldehyde, ammonium acetate, and ethanolamine in [Et2NH2][HSO4] ionic liquid (IL) are studied computationally. The effects of the presence of the cationic and anionic components of the IL on transition states and intermediate structures, acting as a solvent versus as a catalyst, are determined. In IL‐free medium, carbonyl hydroxylation when using a nucleophile (ammonia) proceeds with a Gibbs free energy (ΔG ≠) barrier of 49.4 kcal mol−1. Cationic and anionic hydrogen‐bond solute–solvent interactions with the IL decrease the barrier to 35.8 kcal mol−1. [Et2NH2][HSO4] incorporation in the reaction changes the nature of the transition states and decreases the energy barriers dramatically, creating a catalytic effect. For example, carbonyl hydroxylation proceeds via two transition states, first proton donation to the carbonyl (ΔG ≠=9.2 kcal mol−1) from [Et2NH2]+, and then deprotonation of ammonia (ΔG ≠=14.3) via Et2NH. Likewise, incorporation of the anion component [HSO4]− of the IL gives comparable activation energies along the same reaction route and the lowest transition state for the product formation step. We propose a dual catalytic IL effect for the mechanism of imidazole formation. The computations demonstrate a clear distinction between IL solvent effects on the reaction and IL catalysis. PMID:27777839

  4. Chemical Insights into the Design and Development of Face-Centered Cubic Ruthenium Catalysts for Fischer-Tropsch Synthesis.

    PubMed

    Li, Wei-Zhen; Liu, Jin-Xun; Gu, Jun; Zhou, Wu; Yao, Si-Yu; Si, Rui; Guo, Yu; Su, Hai-Yan; Yan, Chun-Hua; Li, Wei-Xue; Zhang, Ya-Wen; Ma, Ding

    2017-02-15

    Ruthenium is a promising low-temperature catalyst for Fischer-Tropsch synthesis (FTS). However, its scarcity and modest specific activity limit its widespread industrialization. We demonstrate here a strategy for tuning the crystal phase of catalysts to expose denser and active sites for a higher mass-specific activity. Density functional theory calculations show that upon CO dissociation there are a number of open facets with modest barrier available on the face-centered cubic (fcc) Ru but only a few step edges with a lower barrier on conventional hexagonal-closest packed (hcp) Ru. Guided by theoretical calculations, water-dispersible fcc Ru catalysts containing abundant open facets were synthesized and showed an unprecedented mass-specific activity in the aqueous-phase FTS, 37.8 molCO·molRu(-1)·h(-1) at 433 K. The mass-specific activity of the fcc Ru catalysts with an average size of 6.8 nm is about three times larger than the previous best hcp catalyst with a smaller size of 1.9 nm and a higher specific surface area. The origin of the higher mass-specific activity of the fcc Ru catalysts is identified experimentally from the 2 orders of magnitude higher density of the active sites, despite its slightly higher apparent barrier. Experimental results are in excellent agreement with prediction of theory. The great influence of the crystal phases on site distribution and their intrinsic activities revealed here provides a rationale design of catalysts for higher mass-specific activity without decrease of the particle size.

  5. Distribution and factors affecting adsorption of sterols in the surface sediments of Bosten Lake and Manas Lake, Xinjiang.

    PubMed

    Liu, Jiang; Yao, Xiaorui; Lu, Jianjiang; Qiao, Xiuwen; Liu, Zilong; Li, Shanman

    2016-03-01

    This study investigated the concentrations and distribution of eight sterol compounds in the surface sediments of Bosten Lake and Manas Lake, Xinjiang, China. The ratios of sterols as diagnostic indices were used to identify pollution sources. The sediment of the two lakes was selected as an adsorbent to investigate the adsorption behaviour of sterols. Results showed that the sterols were widely distributed in the sediments of the lakes in the study areas. The total concentrations of the detected sterols in Bosten Lake and in Manas Lake were 1.584-27.897 and 2.048-18.373 μg g(-1)∙dw, respectively. In all of the sampling sites, the amount of faecal sterols was less than that of plant sterols. β-sitosterol was the dominant plant sterol with a mean concentration of 2.378 ± 2.234 μg g(-1)∙dw; cholesterol was the most abundant faecal sterol with a mean concentration of 1.060 ± 1.402 μg g(-1)∙dw. The pollution level was higher in Bosten Lake than in Manas Lake. Majority of the ratios clearly demonstrated that the contamination by human faecal sources was occurring at stations which are adjacent to residential areas and water inlets. The adsorption behaviour of sterols to sediment suggested that the sterol adsorption coefficients were reduced as temperature increased. As salinity increased, the adsorption quantity also increased. As pH increased, the sediment adsorption of sterol slightly increased because the strong alkaline solution is not conducive to the adsorption of sterols. The ratios between sterols did not change largely with the change in external factors.

  6. Insights into Stabilization of the 99TcVO Core for Synthesis of 99TcVO Compounds

    SciTech Connect

    McGregor, Donna; Burton-Pye, Benjamin P.; Lukens, Wayne W.; Howell, Robertha C.; Francesconi, Lynn C.

    2014-01-01

    Synthesis of technetium-99 (99Tc; t1/2: 2.1 105 years, max: 253 keV) materials is of importance in studies of the nuclear fuel cycle where Tc is a major fission product (6percent thermal yield from 235U and 239Pu), in understanding radioactive tank waste composition, and in identifying 99mTc compounds for nuclear medicine imaging. One of the most useful synthetic starting materials, (NBu4)TcOCl4, is susceptible to disproportionation in water to form TcO4 and TcIV species, especially TcO2 2H2O. This unwanted reaction is especially problematic when working with ligands bearing hard donor atoms, such as oxygen, where the stability with the soft TcV=O3+ core may be low. Polyoxometalates (POMs) are such ligands. They possess defect sites with four hard oxygen atoms and show low (ca. 108) stability constants with transition metals. Tc complexes of POMs are molecular-level models for Tc metal oxide solid-state materials and can provide information on coordination and redox environments of metal oxides that stabilize low-valent Tc. In order to synthesize pure Tc POM complexes [TcVO(1-P2W17O61)]7 (TcVO-1) and [TcVO(2-P2W17O61)]7 (TcVO-2) from (NBu4)TcOCl4, we have identified strategies that minimize formation of TcIV species and optimize the formation of pure TcV species. The parameters that we consider are the amount of ethylene glycol, which is employed as a transfer ligand to prevent hydrolysis of (NBu4)TcOCl4, and the precipitating agent. The TcIV species that contaminates the non-optimized syntheses is likely a TcIV -oxido-bridged dimer [TcIV-(-O)2-TcIV]. We also employ a novel procedure where the 2 ligand is photoactivated and reduced (in the presence of a sacrificial electron donor) to subsequently reduce TcVIIO4 to an isolatable TcVO-2 product that is remarkably free of TcIV.

  7. Controls on northern wetland methane emissions: insights from regional synthesis studies and the Alaska Peatland Experiment (APEX)

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Euskirchen, E. S.; Czimczik, C. I.; Waldrop, M. P.; Olefeldt, D.; Fan, Z.; Kane, E. S.; McGuire, A. D.; Harden, J. W.

    2014-12-01

    Wetlands are the largest natural source of atmospheric methane. Static chambers have been used to quantify variation in wetland CH4 flux for many decades. Regional to global scale synthesis studies of static chamber measurements show that relationships between temperature, water availability and CH4 emissions depend on wetland type (bog, fen, swamp), region (tropical, temperate, arctic) and disturbance. For example, while water table position and temperature serve as the dominant controls on bog and swamp CH4 flux, vegetation is an important control on emissions from fens. These studies highlight the fact that wetland types have distinct controls on CH4 emissions; however, it is unlikely that modeling of wetland CH4 flux will improve without a better mechanistic understanding of the processes underlying CH4 production, transport, and oxidation. At the Alaska Peatland Experiment, we are quantifying CH4 emission using static chambers, automated chambers, and towers. Our sites vary in permafrost regime, including groundwater fens without permafrost, forested peat plateaus with intact permafrost, and collapse scar bogs formed through permafrost thaw. Experimental studies that examine plant and microbial responses to altered water table position and soil temperature are complemented by a gradient approach, where we use a space-for-time substitutions to examine the consequences of thaw on time-scales of decades to centuries. Our results thus far have documented the importance of soil rewetting in governing large CH4 fluxes from northern wetland soils. Accounting for CH4, our collapse scar bog significantly contributed to the global warming potential of the landscape. A major objective of our work is to explore the role of permafrost C release in greenhouse gas fluxes from wetland soils, which we are assessing using radiocarbon as a natural tracer. We have shown, for example, that ebullition of CH4 is dominated by recently fixed C, but a significant fraction of CH4 in

  8. Effect of ethanol on the sterols of the fission yeast Schizosaccharomyces pombe.

    PubMed

    Koukkou, A I; Tsoukatos, D; Drainas, C

    1993-08-01

    Ergosterol, lanosterol and two further unidentified sterols were detected and quantified in Schizosaccharomyces pombe cell extracts. In cells grown under anaerobic conditions, the levels of these sterols were dramatically reduced with a concomitant increase of their squalene precursor as compared with cells growing under aerobic conditions. Presence of ethanol resulted in a decrease in the sterol content under aerobic conditions. On the contrary, under anaerobic conditions presence of ethanol resulted in a three-fold increase of total sterols. Lanosterol was the main constituent of this elevation. It is suggested that lanosterol in parallel with unsaturated fatty acids is responsible for maintaining membrane integrity of S. pombe cells growing in the presence of ethanol.

  9. Plant Sterols as Dietary Adjuvants in the Reduction of Cardiovascular Risk: Theory and Evidence

    PubMed Central

    Patch, Craig S; Tapsell, Linda C; Williams, Peter G; Gordon, Michelle

    2006-01-01

    Plant sterol-enriched foods are an effective dietary adjuvant in reducing cardiovascular risk by lowering total cholesterol and low density lipoprotein-cholesterol (LDL-C) in serum by up to ∼15%. The mechanism of action of plant sterols is different from those of 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) and thus their effect is additive. Combining plant sterols with other dietary components known to reduce cholesterol in a portfolio approach has proven to be most effective for reduction of hypercholesterolemia and provide an alternative treatment option for clinicians. Plant sterol-enriched foods provides clinicians with a relatively cheap, safe, and effective way to help patients manage their cardiovascular risk. PMID:17319460

  10. Isolation of a biodegradable sterol-rich fraction from industrial wastes.

    PubMed

    Dias, A C P; Fernandes, P; Cabral, J M S; Pinheiro, H M

    2002-05-01

    Several industrial waste materials were screened for their sterol content. The possibility of using these industrial by-products as sterol sources for the microbiological production of 4-androsten-3,17-dione (AD) and 1,4-androsta-diene-3,17-dione (ADD) was investigated. Two methods of obtaining the sterol fraction from wastes were developed. Sterol-rich (96-98%) fractions were isolated in a yield above 70%, from a tall-oil effluent of a paper pulp industry and from edible-oil deodorizates. These fractions were subsequently used as a substrate for microbial degradation by a Mycobacterium sp. strain and proved to be easily converted to AD and ADD.

  11. Investigation of the Sterol Composition and Azole Resistance in Field Isolates of Septoria tritici

    PubMed Central

    Joseph-Horne, T.; Hollomon, D.; Manning, N.; Kelly, S. L.

    1996-01-01

    We report here a biochemical study of resistance to azole antifungal agents in a field isolate (S-27) of a fungal phytopathogen. Isolates of Septoria tritici were compared in vitro, and their responses reflected that observed in the field, with S-27 exhibiting resistance relative to RL2. In untreated cultures, both RL2 and S-27 contained isomers of ergosterol and ergosta-5,7-dienol, although in differing concentrations. Under azole treatment, this phytopathogen exhibited a response similar to that of other pathogenic fungi, with a reduction in desmethyl sterols and an accumulation of 14(alpha)-methyl sterols, indicative of inhibition of the P450-mediating sterol 14(alpha)-demethylase. Growth arrest was attributed to the reduction of ergosterol combined with an accumulation of nonutilizable sterols. Strain S-27 exhibited an azole-resistant phenotype which was correlated with decreased cellular content of azole. PMID:16535210

  12. Hair and skin sterols in normal mice and those with deficient dehydrosterol reductase (DHCR7), the enzyme associated with Smith-Lemli-Opitz syndrome.

    PubMed

    Serra, Montserrat; Matabosch, Xavier; Ying, Lee; Watson, Gordon; Shackleton, Cedric

    2010-11-01

    Our recent studies have focused on cholesterol synthesis in mouse models for 7-dehydrosterolreductase (DHCR7) deficiency, also known as Smith-Lemli-Opitz syndrome. Investigations of such mutants have relied on tissue and blood levels of the cholesterol precursor 7-dehydrocholesterol (7DHC) and its 8-dehydro isomer. In this investigation by gas chromatography/mass spectrometry (GC/MS) we have identified and quantified cholesterol and its precursors (7DHC, desmosterol, lathosterol, lanosterol and cholest-7,24-dien-3β-ol) in mouse hair. The components were characterized and their concentrations were compared to those found in mouse skin and serum. Hair appeared unique in that desmosterol was a major sterol component, almost matching in concentration cholesterol itself. In DHCR7 deficient mice, dehydrodesmosterol (DHD) was the dominant hair Δ(7) sterol. Mutant mouse hair had much higher concentrations of 7-dehydrosterols relative to cholesterol than did serum or tissue at all ages studied. The 7DHC/C ratio in hair was typically about sevenfold the value in serum or skin and the DHD/D ratio was 100× that of the serum 7DHC/C ratio. Mutant mice compensate for their DHCR7 deficiency with maturity, and the tissue and blood 7DHC/C become close to normal. That hair retains high relative concentrations of the dehydro precursors suggests that the apparent up-regulation of Dhcr7 seen in liver is slower to develop at the site of hair cholesterol synthesis.

  13. Characterization, mutagenesis and mechanistic analysis of an ancient algal sterol C24-methyltransferase: Implications for understanding sterol evolution in the green lineage

    PubMed Central

    Haubrich, Brad A.; Collins, Emily K.; Howard, Alicia L.; Wang, Qian; Snell, William J.; Miller, Matthew B.; Thomas, Crista D.; Pleasant, Stephanie K.; Nes, W. David

    2016-01-01

    Sterol C24-methyltransferases (SMTs) constitute a group of sequence-related proteins that catalyze the pattern of sterol diversity across eukaryotic kingdoms. The only gene for sterol alkylation in green algae was identified and the corresponding catalyst from Chlamydomonas reinhardtii (Cr) was characterized kinetically and for product distributions. The properties of CrSMT were similar to those predicted for an ancient SMT expected to possess broad C3-anchoring requirements for substrate binding and formation of 24β-methyl/ethyl Δ25(27)-olefin products typical of primitive organisms. Unnatural Δ24(25)-sterol substrates, missing a C4β-angular methyl group involved with binding orientation, convert to product ratios in favor of Δ24(28)-products. Remodeling the active site to alter the electronics of Try110 (to Leu) results in delayed timing of the hydride migration from methyl attack of the Δ24-bond, that thereby produces metabolic switching of product ratios in favor of Δ25(27)-olefins or impairs the second C1-transfer activity. Incubation of [27-13C]lanosterol or [methyl-2H3]SAM as co-substrates established the CrSMT catalyzes a sterol methylation pathway by the “algal” Δ25(27)-olefin route, where methylation proceeds by a conserved SN2 reaction and de-protonation proceeds from the pro-Z methyl group on lanosterol corresponding to C27. This previously unrecognized catalytic competence for an enzyme of sterol biosynthesis, together with phylogenomic analyses, suggest that mutational divergence of a promiscuous SMT produced substrate- and phyla-specific SMT1 (catalyzes first biomethylation) and SMT2 (catalyzes second biomethylation) isoforms in red and green algae, respectively, and in the case of SMT2 selection afforded modification in reaction channeling necessary for the switch in ergosterol (24β-methyl) biosynthesis to stigmasterol (24α-ethyl) biosynthesis during the course of land plant evolution. PMID:25132279

  14. Characterization, mutagenesis and mechanistic analysis of an ancient algal sterol C24-methyltransferase: Implications for understanding sterol evolution in the green lineage.

    PubMed

    Haubrich, Brad A; Collins, Emily K; Howard, Alicia L; Wang, Qian; Snell, William J; Miller, Matthew B; Thomas, Crista D; Pleasant, Stephanie K; Nes, W David

    2015-05-01

    Sterol C24-methyltransferases (SMTs) constitute a group of sequence-related proteins that catalyze the pattern of sterol diversity across eukaryotic kingdoms. The only gene for sterol alkylation in green algae was identified and the corresponding catalyst from Chlamydomonas reinhardtii (Cr) was characterized kinetically and for product distributions. The properties of CrSMT were similar to those predicted for an ancient SMT expected to possess broad C3-anchoring requirements for substrate binding and formation of 24β-methyl/ethyl Δ(25(27))-olefin products typical of primitive organisms. Unnatural Δ(24(25))-sterol substrates, missing a C4β-angular methyl group involved with binding orientation, convert to product ratios in favor of Δ(24(28))-products. Remodeling the active site to alter the electronics of Try110 (to Leu) results in delayed timing of the hydride migration from methyl attack of the Δ(24)-bond, that thereby produces metabolic switching of product ratios in favor of Δ(25(27))-olefins or impairs the second C1-transfer activity. Incubation of [27-(13)C]lanosterol or [methyl-(2)H3]SAM as co-substrates established the CrSMT catalyzes a sterol methylation pathway by the "algal" Δ(25(27))-olefin route, where methylation proceeds by a conserved SN2 reaction and de-protonation proceeds from the pro-Z methyl group on lanosterol corresponding to C27. This previously unrecognized catalytic competence for an enzyme of sterol biosynthesis, together with phylogenomic analyses, suggest that mutational divergence of a promiscuous SMT produced substrate- and phyla-specific SMT1 (catalyzes first biomethylation) and SMT2 (catalyzes second biomethylation) isoforms in red and green algae, respectively, and in the case of SMT2 selection afforded modification in reaction channeling necessary for the switch in ergosterol (24β-methyl) biosynthesis to stigmasterol (24α-ethyl) biosynthesis during the course of land plant evolution.

  15. Azole fungicides affect mammalian steroidogenesis by inhibiting sterol 14 alpha-demethylase and aromatase.

    PubMed

    Zarn, Jürg A; Brüschweiler, Beat J; Schlatter, Josef R

    2003-03-01

    Azole compounds play a key role as antifungals in agriculture and in human mycoses and as non-steroidal antiestrogens in the treatment of estrogen-responsive breast tumors in postmenopausal women. This broad use of azoles is based on their inhibition of certain pathways of steroidogenesis by high-affinity binding to the enzymes sterol 14-alpha-demethylase and aromatase. Sterol 14-alpha-demethylase is crucial for the production of meiosis-activating sterols, which recently were shown to modulate germ cell development in both sexes of mammals. Aromatase is responsible for the physiologic balance of androgens and estrogens. At high doses, azole fungicides and other azole compounds affect reproductive organs, fertility, and development in several species. These effects may be explained by inhibition of sterol 14-alpha-demethylase and/or aromatase. In fact, several azole compounds were shown to inhibit these enzymes in vitro, and there is also strong evidence for inhibiting activity in vivo. Furthermore, the specificity of the enzyme inhibition of several of these compounds is poor, both with respect to fungal versus nonfungal sterol 14-alpha-demethylases and versus other P450 enzymes including aromatase. To our knowledge, this is the first review on sterol 14-alpha-demethylase and aromatase as common targets of azole compounds and the consequence for steroidogenesis. We conclude that many azole compounds developed as inhibitors of fungal sterol 14-alpha-demethylase are inhibitors also of mammalian sterol 14-alpha-demethylase and mammalian aromatase with unknown potencies. For human health risk assessment, data on comparative potencies of azole fungicides to fungal and human enzymes are needed.

  16. Plant sterols/stanols as cholesterol lowering agents: A meta-analysis of randomized controlled trials

    PubMed Central

    AbuMweis, Suhad S.; Barake, Roula; Jones, Peter J.H.

    2008-01-01

    Background Consumption of plant sterols has been reported to reduce low density lipoprotein (LDL) cholesterol concentrations by 5–15%. Factors that affect plant sterol efficacy are still to be determined. Objectives To more precisely quantify the effect of plant sterol enriched products on LDL cholesterol concentrations than what is reported previously, and to identify and quantify the effects of subjects’ characteristics, food carrier, frequency and time of intake on efficacy of plant sterols as cholesterol lowering agents. Design Fifty-nine eligible randomized clinical trials published from 1992 to 2006 were identified from five databases. Weighted mean effect sizes were calculated for net differences in LDL levels using a random effect model. Results Plant sterol containing products decreased LDL levels by 0.31 mmol/L (95% CI, –0.35 to –0.27, P= < 0.0001) compared with placebo. Between trial heterogeneity was evident (Chi-square test, P = <0.0001) indicating that the observed differences between trial results were unlikely to have been caused by chance. Reductions in LDL levels were greater in individuals with high baseline LDL levels compared with those with normal to borderline baseline LDL levels. Reductions in LDL were greater when plant sterols were incorporated into fat spreads, mayonnaise and salad dressing, milk and yoghurt comparing with other food products such as croissants and muffins, orange juice, non-fat beverages, cereal bars, and chocolate. Plant sterols consumed as a single morning dose did not have a significant effect on LDL cholesterol levels. Conclusion Plant sterol containing products reduced LDL concentrations but the reduction was related to individuals’ baseline LDL levels, food carrier, and frequency and time of intake. PMID:19109655

  17. Azole fungicides affect mammalian steroidogenesis by inhibiting sterol 14 alpha-demethylase and aromatase.

    PubMed Central

    Zarn, Jürg A; Brüschweiler, Beat J; Schlatter, Josef R

    2003-01-01

    Azole compounds play a key role as antifungals in agriculture and in human mycoses and as non-steroidal antiestrogens in the treatment of estrogen-responsive breast tumors in postmenopausal women. This broad use of azoles is based on their inhibition of certain pathways of steroidogenesis by high-affinity binding to the enzymes sterol 14-alpha-demethylase and aromatase. Sterol 14-alpha-demethylase is crucial for the production of meiosis-activating sterols, which recently were shown to modulate germ cell development in both sexes of mammals. Aromatase is responsible for the physiologic balance of androgens and estrogens. At high doses, azole fungicides and other azole compounds affect reproductive organs, fertility, and development in several species. These effects may be explained by inhibition of sterol 14-alpha-demethylase and/or aromatase. In fact, several azole compounds were shown to inhibit these enzymes in vitro, and there is also strong evidence for inhibiting activity in vivo. Furthermore, the specificity of the enzyme inhibition of several of these compounds is poor, both with respect to fungal versus nonfungal sterol 14-alpha-demethylases and versus other P450 enzymes including aromatase. To our knowledge, this is the first review on sterol 14-alpha-demethylase and aromatase as common targets of azole compounds and the consequence for steroidogenesis. We conclude that many azole compounds developed as inhibitors of fungal sterol 14-alpha-demethylase are inhibitors also of mammalian sterol 14-alpha-demethylase and mammalian aromatase with unknown potencies. For human health risk assessment, data on comparative potencies of azole fungicides to fungal and human enzymes are needed. PMID:12611652

  18. Total, free and conjugated sterolic forms in three microalgae used in mariculture.

    PubMed

    Mohammady, Nagwa Gamal

    2004-01-01

    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 conjugated forms. However, the total sterol content of T. chuii was about 325 microg/g dry wt, most of it was concentrated amongst 24-methylcholesta-5,24-diene-3beta-ol and 24-methylcholest-5-en-3beta-ol. On the other hand, the majority of the fractions were distributed in the free form. The total sterol content of N. salina was about 180 microg/g dry wt, cholesterol was the major fraction that was detected. Nevertheless, the dominant distribution forms were esterified. While in S. costatum, the total sterol content was 76 microg/g dry wt, approximately most fractions are quantitatively alike and dominated in the free form. Furthermore, our study shows clearly that most sterols are not distributed regularly within each form, a result that encouraged us to suggest a distribution of specific sterol fraction as a free or conjugated can be used as a serving tool in chemotaxonomic studies.

  19. Free, esterified and residual bound sterols in Black Sea Unit I sediments

    NASA Astrophysics Data System (ADS)

    de Leeuw, J. W.; Rijpstra, W. Irene C.; Schenck, P. A.; Volkman, J. K.

    1983-03-01

    Detailed compositional data for the sterols isolated from a surface, Unit I, sediment from the Black Sea are reported. A procedure based on digitonin precipitation has been used to separate the more abundant free sterols from those occurring in esterified forms. Saponification of the solvent extracted sediment residue liberated only a small quantity of residual bound sterols in contrast to studies of other sediments. 4-Methylsterols are much more abundant than 4-desmethylsterols in both the free and esterified sterol fractions which we attribute to a major dinoflagellate input, as in deeper Unit II sediment. The desmethylsterol fraction appears to derive from a variety of sources including dinoflagellates, coccolithophores, diatoms, terrigenous detritus and perhaps invertebrates. 5α(H)-Stanols are particularly abundant in the free sterol fraction. An analysis of the stanol/stenol ratios suggests that the 4-desmethyl-5α(H)-stanols are the result of specific microbial reductions of Δ 5-sterols and/or the reflection of a contribution of stanol containing source organisms.

  20. Quantitation of fatty acids, sterols, and tocopherols in turpentine (Pistacia terebinthus Chia) growing wild in Turkey.

    PubMed

    Matthäus, Bertrand; Ozcan, Mehmet Musa

    2006-10-04

    The chemical composition (fatty acids, tocopherols, and sterols) of the oil from 14 samples of turpentine (Pistacia terebinthus L.) fruits is presented in this study. The oil content of the samples varied in a relatively small range between 38.4 g/100 g and 45.1 g/100 g. The dominating fatty acid of the oil is oleic acid, which accounted for 43.0 to 51.3% of the total fatty acids. The total content of vitamin E active compounds in the oils ranged between 396.8 and 517.7 mg/kg. The predominant isomers were alpha- and gamma-tocopherol, with approximate equal amounts between about 110 and 150 mg/kg. The seed oil of P. terebinthus also contained different tocotrienols, with gamma-tocotrienol as the dominate compound of this group, which amounted to between 79 and 114 mg/kg. The total content of sterols of the oils was determined to be between 1341.3 and 1802.5 mg/kg, with beta-sitosterol as the predominent sterol that accounted for more than 80% of the total amount of sterols. Other sterols in noteworthy amounts were campesterol, Delta5-avenasterol, and stigmasterol, which came to about 3-5% of the total sterols.

  1. Sterol metabolism in the filasterean Capsaspora owczarzaki has features that resemble both fungi and animals

    PubMed Central

    Molina, María Celeste; Ruiz-Trillo, Iñaki; Uttaro, Antonio D.

    2016-01-01

    Sterols are essential for several physiological processes in most eukaryotes. Sterols regulate membrane homeostasis and participate in different signalling pathways not only as precursors of steroid hormones and vitamins, but also through its role in the formation of lipid rafts. Two major types of sterols, cholesterol and ergosterol, have been described so far in the opisthokonts, the clade that comprise animals, fungi and their unicellular relatives. Cholesterol predominates in derived bilaterians, whereas ergosterol is what generally defines fungi. We here characterize, by a combination of bioinformatic and biochemical analyses, the sterol metabolism in the filasterean Capsaspora owczarzaki, a close unicellular relative of animals that is becoming a model organism. We found that C. owczarzaki sterol metabolism combines enzymatic activities that are usually considered either characteristic of fungi or exclusive to metazoans. Moreover, we observe a differential transcriptional regulation of this metabolism across its life cycle. Thus, C. owczarzaki alternates between synthesizing 7-dehydrocholesterol de novo, which happens at the cystic stage, and the partial conversion—via a novel pathway—of incorporated cholesterol into ergosterol, the characteristic fungal sterol, in the filopodial and aggregative stages. PMID:27383626

  2. Sterol metabolism in the filasterean Capsaspora owczarzaki has features that resemble both fungi and animals.

    PubMed

    Najle, Sebastián R; Molina, María Celeste; Ruiz-Trillo, Iñaki; Uttaro, Antonio D

    2016-07-01

    Sterols are essential for several physiological processes in most eukaryotes. Sterols regulate membrane homeostasis and participate in different signalling pathways not only as precursors of steroid hormones and vitamins, but also through its role in the formation of lipid rafts. Two major types of sterols, cholesterol and ergosterol, have been described so far in the opisthokonts, the clade that comprise animals, fungi and their unicellular relatives. Cholesterol predominates in derived bilaterians, whereas ergosterol is what generally defines fungi. We here characterize, by a combination of bioinformatic and biochemical analyses, the sterol metabolism in the filasterean Capsaspora owczarzaki, a close unicellular relative of animals that is becoming a model organism. We found that C. owczarzaki sterol metabolism combines enzymatic activities that are usually considered either characteristic of fungi or exclusive to metazoans. Moreover, we observe a differential transcriptional regulation of this metabolism across its life cycle. Thus, C. owczarzaki alternates between synthesizing 7-dehydrocholesterol de novo, which happens at the cystic stage, and the partial conversion-via a novel pathway-of incorporated cholesterol into ergosterol, the characteristic fungal sterol, in the filopodial and aggregative stages.

  3. Cytochrome P450 metabolism of the post-lanosterol intermediates explains enigmas of cholesterol synthesis.

    PubMed

    Ačimovič, Jure; Goyal, Sandeep; Košir, Rok; Goličnik, Marko; Perše, Martina; Belič, Ales; Urlep, Žiga; Guengerich, F Peter; Rozman, Damjana

    2016-06-23

    Cholesterol synthesis is among the oldest metabolic pathways, consisting of the Bloch and Kandutch-Russell branches. Following lanosterol, sterols of both branches are proposed to be dedicated to cholesterol. We challenge this dogma by mathematical modeling and with experimental evidence. It was not possible to explain the sterol profile of testis in cAMP responsive element modulator tau (Crem τ) knockout mice with mathematical models based on textbook pathways of cholesterol synthesis. Our model differs in the inclusion of virtual sterol metabolizing enzymes branching from the pathway. We tested the hypothesis that enzymes from the cytochrome P450 (CYP) superfamily can participate in the catalysis of non-classical reactions. We show that CYP enzymes can metabolize multiple sterols in vitro, establishing novel branching points of cholesterol synthesis. In conclusion, sterols of cholesterol synthesis can be oxidized further to metabolites not dedicated to production of cholesterol. Additionally, CYP7A1, CYP11A1, CYP27A1, and CYP46A1 are parts of a broader cholesterol synthesis network.

  4. Cytochrome P450 metabolism of the post-lanosterol intermediates explains enigmas of cholesterol synthesis

    NASA Astrophysics Data System (ADS)

    Ačimovič, Jure; Goyal, Sandeep; Košir, Rok; Goličnik, Marko; Perše, Martina; Belič, Ales; Urlep, Žiga; Guengerich, F. Peter; Rozman, Damjana

    2016-06-01

    Cholesterol synthesis is among the oldest metabolic pathways, consisting of the Bloch and Kandutch-Russell branches. Following lanosterol, sterols of both branches are proposed to be dedicated to cholesterol. We challenge this dogma by mathematical modeling and with experimental evidence. It was not possible to explain the sterol profile of testis in cAMP responsive element modulator tau (Crem τ) knockout mice with mathematical models based on textbook pathways of cholesterol synthesis. Our model differs in the inclusion of virtual sterol metabolizing enzymes branching from the pathway. We tested the hypothesis that enzymes from the cytochrome P450 (CYP) superfamily can participate in the catalysis of non-classical reactions. We show that CYP enzymes can metabolize multiple sterols in vitro, establishing novel branching points of cholesterol synthesis. In conclusion, sterols of cholesterol synthesis can be oxidized further to metabolites not dedicated to production of cholesterol. Additionally, CYP7A1, CYP11A1, CYP27A1, and CYP46A1 are parts of a broader cholesterol synthesis network.

  5. Sustained and selective suppression of intestinal cholesterol synthesis by Ro 48-8071, an inhibitor of 2,3-oxidosqualene:lanosterol cyclase, in the BALB/c mouse.

    PubMed

    Chuang, Jen-Chieh; Valasek, Mark A; Lopez, Adam M; Posey, Kenneth S; Repa, Joyce J; Turley, Stephen D

    2014-04-01

    The small intestine plays a fundamentally important role in regulating whole body cholesterol balance and plasma lipoprotein composition. This is articulated through the interplay of a constellation of genes that ultimately determines the net amount of chylomicron cholesterol delivered to the liver. Major advances in our insights into regulation of the cholesterol absorption pathway have been made using genetically manipulated mouse models and agents such as ezetimibe. One unresolved question is how a sustained pharmacological inhibition of intestinal cholesterol synthesis in vivo may affect cholesterol handling by the absorptive cells. Here we show that the lanosterol cyclase inhibitor, Ro 48-8071, when fed to BALB/c mice in a chow diet (20 mg/day/kg body weight), leads to a rapid and sustained inhibition (>50%) of cholesterol synthesis in the whole small intestine. Sterol synthesis was also reduced in the large intestine and stomach. In contrast, hepatic cholesterol synthesis, while markedly suppressed initially, rebounded to higher than baseline rates within 7 days. Whole body cholesterol synthesis, fractional cholesterol absorption, and fecal neutral and acidic sterol excretion were not consistently changed with Ro 48-8071 treatment. There were no discernible effects of this agent on intestinal histology as determined by H&E staining and the level of Ki67, an index of proliferation. The mRNA expression for multiple genes involved in intestinal cholesterol regulation including NPC1L1 was mostly unchanged although there was a marked rise in the mRNA level for the PXR target genes CYP3A11 and CES2A.

  6. Synthesis and supramolecular studies of chiral boronated platinum(II) complexes: insights into the molecular recognition of carboranes by β-cyclodextrin.

    PubMed

    Ching, H Y Vincent; Clifford, Sarah; Bhadbhade, Mohan; Clarke, Ronald J; Rendina, Louis M

    2012-11-05

    The synthesis and characterisation of a novel isomeric family of closo-carborane-containing Pt(II) complexes ((R/S)-(1-4)⋅2 NO(3)) are reported. Related complexes (5⋅NO(3) and 6⋅NO(3)) that contain the 7,8-nido-carborane cluster were obtained from the selective deboronation of the 1,2-closo-carborane analogues. The corresponding water-soluble supramolecular 1:1 host-guest β-cyclodextrin (β-CD) adducts ((R/S)-(1-4)⋅β-CD⋅2 NO(3)) were also prepared and fully characterised. HR-ESI-MS experiments confirmed the presence of the host-guest adducts, and 2D-(1) H{(11)B} ROESY NMR studies showed that the boron clusters enter the β-CD from the side of the wider annulus. Isothermal titration calorimetry (ITC) experiments revealed enthalpically driven 1:1 and higher-order supramolecular interactions between β-CD and (R/S)-(1-4)⋅2 NO(3) in aqueous solution. A comparison of the predominate 1:1 binding mode established that the affinity of β-CD for the guest molecule is mainly influenced by the pyridyl ring substitution pattern and chirality of the host, whilst the nature of the closo-carborane isomer also plays some role, with the most favourable structural features for β-CD binding being the presence of the 4-pyridyl ring, 1,12-closo-carborane, and an S configuration. The results reported here represent the first comprehensive calorimetric study of the supramolecular interactions between closo-carborane compounds and β-CD, and it provides fascinating insights into the structural features influencing the thermodynamics of this phenomenon.

  7. Chemical Synthesis of Staphyloferrin B Affords Insight into the Molecular Structure, Iron Chelation, and Biological Activity of a Polycarboxylate Siderophore Deployed by the Human Pathogen Staphylococcus aureus.

    PubMed

    Madsen, Julie L H; Johnstone, Timothy C; Nolan, Elizabeth M

    2015-07-22

    Staphyloferrin B (SB) is a citrate-based polycarboxylate siderophore produced and utilized by the human pathogen Staphylococcus aureus for acquiring iron when colonizing the vertebrate host. The first chemical synthesis of SB is reported, which enables further molecular and biological characterization and provides access to structural analogues of the siderophore. Under conditions of iron limitation, addition of synthetic SB to bacterial growth medium recovered the growth of the antibiotic resistant community isolate S. aureus USA300 JE2. Two structural analogues of SB, epiSB and SBimide, were also synthesized and employed to investigate how epimerization of the citric acid moiety or imide formation influence its function as a siderophore. Epimerization of the citric acid stereocenter perturbed the iron-binding properties and siderophore function of SB as evidenced by experimental and computational modeling studies. Although epiSB provided growth recovery to S. aureus USA300 JE2 cultured in iron-deficient medium, the effect was attenuated relative to that of SB. Moreover, SB more effectively sequestered the Fe(III) bound to human holo-transferrin, an iron source of S. aureus, than epiSB. SBimide is an imide analogous to the imide forms of other citric acid siderophores that are often observed when these molecules are isolated from natural sources. Here, SBimide is shown to be unstable, converting to native SB at physiological pH. SB is considered to be a virulence factor of S. aureus, a pathogen that poses a particular threat to public health because of the number of drug-resistant strains emerging in hospital and community settings. Iron acquisition by S. aureus is important for its ability to colonize the human host and cause disease, and new chemical insights into the structure and function of SB will inform the search for new therapeutic strategies for combating S. aureus infections.

  8. A structural appraisal of sterol carrier protein 2.

    PubMed

    Burgardt, Noelia I; Gianotti, Alejo R; Ferreyra, Raúl G; Ermácora, Mario R

    2017-05-01

    Sterol Carrier Protein 2 (SCP2) has been associated with lipid binding and transfer activities. However, genomic, proteomic, and structural studies revealed that it is an ubiquitous domain of complex proteins with a variety functions in all forms of life. High-resolution structures of representative SCP2 domains are available, encouraging a comprehensive review of the structural basis for its success. Most SCP2 domains pertain to three major families and are frequently found as stand-alone or at the C-termini of lipid related peroxisomal enzymes, acetyltransferases causing bacterial resistance, and bacterial environmentally important sulfatases. We (1) analyzed the structural basis of the fold and the classification of SCP2 domains; (2) identified structure-determined sequence features; (3) compared the lipid binding cavity of SCP2 and other lipid binding proteins; (4) surveyed proposed mechanisms of SCP2 mediated lipid transfer between membranes; and (5) uncovered a possible new function of the SCP2 domain as a protein-protein recognition device.

  9. Faecal sterols as indicators of sewage contamination in estuarine sediments of the Tay Estuary, Scotland: an extended baseline survey

    NASA Astrophysics Data System (ADS)

    Reeves, A. D.; Patton, D.

    2005-06-01

    Sterol ratios are used to identify sources, occurrence and partitioning of faecal matter in sediments of the Tay Estuary, Scotland. The 5β/(5α+5β) ratio is used to discriminate between sewage and biogenic sterol sources by comparing the concentrations of coprostanols to cholesterol plus coprostanols. This index shows unambiguous sewage pollution in the Invergowrie Bay area (values >0.7). The coprostanol/epicoprostanol index is used to differentiate between human and non-human faecal inputs. Ratios confirmed the primary source as human-derived faecal material. The coprostanol/cholesterol ratio was calculated in order to elucidate the contribution of different biogenic sources to the sedimentary sterol budget. Ratios of >1 clearly indicate faecal sterol sources. Invergowrie Bay displayed no sterol signature other than sewage. A biogenic source of cholesterol influenced total sterol concentrations upstream of the City of Dundee. Attention is directed to the potential role of density fronts in compartmentalization of faecal material in bottom sediments.

  10. Postprandial plasma oxyphytosterol concentrations after consumption of plant sterol or stanol enriched mixed meals in healthy subjects.

    PubMed

    Baumgartner, Sabine; Mensink, Ronald P; Konings, Maurice; Schött, Hans-F; Friedrichs, Silvia; Husche, Constanze; Lütjohann, Dieter; Plat, Jogchum

    2015-07-01

    Epidemiological studies have reported inconsistent results on the relationship between increased plant sterol concentrations with cardiovascular risk, which might be related to the formation of oxyphytosterols (plant sterol oxidation products) from plant sterols. However, determinants of oxyphytosterol formation and metabolism are largely unknown. It is known, however, that serum plant sterol concentrations increase after daily consumption of plant sterol enriched products, while concentrations decrease after plant stanol consumption. Still, we have earlier reported that fasting oxyphytosterol concentrations did not increase after consuming a plant sterol- or a plant stanol enriched margarine (3.0g/d of plant sterols or stanols) for 4weeks. Since humans are in a non-fasting state for most part of the day, we have now investigated effects on oxyphytosterol concentrations during the postprandial state. For this, subjects consumed a shake (50g of fat, 12g of protein, 67g of carbohydrates), containing no, or 3.0g of plant sterols or plant stanols. Blood samples were taken up to 8h and after 4h subjects received a second shake (without plant sterols or plant stanols). Serum oxyphytosterol concentrations were determined in BHT-enriched EDTA plasma via GC-MS/MS. 7β-OH-campesterol and 7β-OH-sitosterol concentrations were significantly higher after consumption of a mixed meal enriched with plant sterol esters compared to the control and plant stanol ester meal. These increases were seen only after consumption of the second shake, illustrative for a second meal effect. Non-oxidized campesterol and sitosterol concentrations also increased after plant sterol consumption, in parallel with 7β-OH concentrations and again only after the second meal. Apparently, plant sterols and oxyphytosterols follow the same second meal effect as described for dietary cholesterol. However, the question remains whether the increase in oxyphytosterols in the postprandial phase is due to

  11. Distribution of fecal sterols in surface sediment of Sungai Tebrau, Johor

    NASA Astrophysics Data System (ADS)

    Nordin, N.; Ali, M. M.

    2013-11-01

    Decreasing quality of aquatic environments may harm human health in general. Sewage pollution from human and animal excretions is a major cause of environmental quality depletion. This study investigates the distribution of sewage contamination level in twenty surface sediment samples taken from Sungai Tebrau, Johor. Four principal fecal sterols have been identified and were found in all sediment samples, which are coprostanol, cholesterol, epicoprostanol and also cholestanol. Cholesterol as the major sterol and most abundant compound derived from a variety of sources ranged from 32.92 to 1,100.55 ngg-1 dry weights. Meanwhile, major fecal sterol, coprostanol has the lowest quantity of total sterol in all samples, constituting only 13% of total sterol. It ranged from 12.63 to 565.42 ngg-1 dry weights, but only two stations (ST12 and ST14) are sewage contaminated. Squatters and residential areas are a major contributor of poorly treated sewage into the aquatic environment. Coprostanol concentration alone is not reliable to indicate sewage contamination; diagnostic indices enhance reliability of sterols as a marker for sewage contamination. Indices applied in this study are coprostanol/cholesterol, coprostanol/(coprostanol+cholestanol) and also epicoprostanol/coprostanol. Resultsof coprostanol/cholesterol, coprostanol/(coprostanol+cholestanol) indices supported the findings that both ST12 and ST14 samples are contaminated with sewage. All samples consist of relativelyhigh concentration of epicoprostanol and high ratio value of epicoprostanol/coprostanol. Generally, it can be concluded that these sampling sites are not contaminated with sewage even though fecal sterols were detected in all samples as they were found to be at low concentration.

  12. Effect of plant sterols on the lipid profile of patients with hypercholesterolaemia. Randomised, experimental study

    PubMed Central

    2011-01-01

    Background Studies have been conducted on supplementing the daily diet with plant sterol ester-enriched milk derivatives in order to reduce LDL-cholesterol levels and, consequently, cardiovascular risk. However, clinical practice guidelines on hypercholesterolaemia state that there is not sufficient evidence to recommend their use in subjects with hypercholesterolaemia. The main objective of this study is to determine the efficacy of the intake of 2 g of plant sterol esters a day in lowering LDL-cholesterol levels in patients diagnosed with hypercholesterolaemia. The specific objectives are: 1) to quantify the efficacy of the daily intake of plant sterol esters in lowering LDL-cholesterol, total cholesterol and cardiovascular risk in patients with hypercholesterolaemia; 2) to evaluate the occurrence of adverse effects of the daily intake of plant sterol esters; 3) to identify the factors that determine a greater reduction in lipid levels in subjects receiving plant sterol ester supplements. Methods/Design Randomised, double-blind, placebo controlled experimental trial carried out at family doctors' surgeries at three health centres in the Health Area of Albacete (Spain). The study subjects will be adults diagnosed with "limit" or "defined" hypercholesterolaemia and who have LDL cholesterol levels of 130 mg/dl or over. A dairy product in the form of liquid yoghurt containing 2 g of plant sterol ester per container will be administered daily after the main meal, for a period of 24 months. The control group will receive a daily unit of yogurt not supplemented with plant sterol esters that has a similar appearance to the enriched yoghurt. The primary variable is the change in lipid profile at 1, 3, 6, 12, 18 and 24 months. The secondary variables are: change in cardiovascular risk, adherence to the dairy product, adverse effects, adherence to dietary recommendations, frequency of food consumption, basic physical examination data, health problems, lipid

  13. Sterolic composition of Chétoui virgin olive oil: Influence of geographical origin.

    PubMed

    Temime, Sonia Ben; Manai, Hedia; Methenni, Kaouther; Baccouri, Bechir; Abaza, Leila; Daoud, Douja; Casas, Jacinto Sánchez; Bueno, Emilio Osorio; Zarrouk, Mokhtar

    2008-09-15

    The sterol profile of Tunisian virgin olive oils produced from Chétoui cultivar, the second main variety cultivated in the north of the country, grown under different environmental conditions, was established by gas chromatography using a flame ionisation detector. More than ten compounds were identified and characterised. As expected for virgin olive oil, the main sterols found in all Chétoui olive oils were β-sitosterol, Δ5-avenasterol, campesterol and stigmasterol. Cholesterol, 24-methylenecholesterol, clerosterol, campestanol, sitostanol, Δ7-stigmastenol, Δ5,24-stigmastadienol, and Δ7-avenasterol were also found in all samples, but in lower amounts. Most of these compounds are significantly affected by the geographical origin. The majority of the Chétoui virgin olive oils analysed respected EC Regulation No. 2568, and in all cases total sterol amounts were higher than the minimum limit set by legislation, ranging from 1017 to 1522mg/kg. Two triterpenic dialcohols (erythrodiol and uvaol), were also detected besides the sterolic components. Their content was below the upper legal limit of 4% in all analysed samples, with a range from 1.2% to 3.2%. These results suggest that, besides the genetic factor, environmental conditions influence the sterolic fraction.

  14. Comparison and analysis of fatty acids, sterols, and tocopherols in eight vegetable oils.

    PubMed

    Li, Changmo; Yao, Yunping; Zhao, Guozhong; Cheng, Wen; Liu, Huilin; Liu, Chunyang; Shi, Zhen; Chen, Yao; Wang, Shuo

    2011-12-14

    The similarities and differences of eight vegetable oils produced in China were investigated in terms of their fatty acid, sterol, and tocopherol compositions and subsequent data processing by hierarchical clustering analysis and principal component analysis. The lipid profiles, acquired by analytical techniques tailored to each lipid class, revealed great similarities among the fatty acid profiles of corn and sesame oil as well as few differences in their sterol profiles. It turns out that not only was there great similarity between the fatty acid profiles of corn oil and sesame oil but also there were not too many differences for the sterol profiles. Sunflower and tea-seed oil showed similar sterol compositions, while the tea-seed oil tocopherol was very similar to palm oil. The results demonstrated that the use of only one of these profiles was unreliable for indentifying oil origin and authenticity. In contrast, the use of the sterol or tocopherol profile together with the fatty acid profile more accurately discriminates these oils.

  15. Plasma Membrane Sterol Distribution Resembles the Surface Topography of Living Cells

    PubMed Central

    2007-01-01

    Cholesterol is an important constituent of cellular membranes. It has been suggested that cholesterol segregates into sterol-rich and -poor domains in the plasma membrane, although clear evidence for this is lacking. By fluorescence imaging of the natural sterol dehydroergosterol (DHE), the lateral sterol distribution has been visualized in living cells. The spatial labeling pattern of DHE coincided with surface structures such as ruffles, microvilli, and filopodia with correlation lengths in the range of 0.8–2.5 μm. DHE staining of branched tubules and of nanotubes connecting two cells was detected. Dynamics of DHE in folded and plane membrane regions was comparable as determined by fluorescence recovery after photobleaching. DHE colocalized with fluid membrane-preferring phospholipids in surface structures and at sites of cell attachment as well as in the cleavage furrow of dividing cells, but it was not particularly enriched in those regions. Fluorescent sterol showed homogeneous staining in membrane blebs induced by F-actin disruption. Cross-linking the ganglioside GM1—a putative raft marker—did not affect the cell surface distribution of DHE. The results suggest that spatial heterogeneities of plasma membrane staining of DHE resolvable by light microscopy reflect the cell surface topography but not phase-separated sterol domains in the bilayer plane. PMID:17065557

  16. Plant sterols: factors affecting their efficacy and safety as functional food ingredients

    PubMed Central

    Berger, Alvin; Jones, Peter JH; Abumweis, Suhad S

    2004-01-01

    Plant sterols are naturally occurring molecules that humanity has evolved with. Herein, we have critically evaluated recent literature pertaining to the myriad of factors affecting efficacy and safety of plant sterols in free and esterified forms. We conclude that properly solubilized 4-desmetyl plant sterols, in ester or free form, in reasonable doses (0.8–1.0 g of equivalents per day) and in various vehicles including natural sources, and as part of a healthy diet and lifestyle, are important dietary components for lowering low density lipoprotein (LDL) cholesterol and maintaining good heart health. In addition to their cholesterol lowering properties, plant sterols possess anti-cancer, anti-inflammatory, anti-atherogenicity, and anti-oxidation activities, and should thus be of clinical importance, even for those individuals without elevated LDL cholesterol. The carotenoid lowering effect of plant sterols should be corrected by increasing intake of food that is rich in carotenoids. In pregnant and lactating women and children, further study is needed to verify the dose required to decrease blood cholesterol without affecting fat-soluble vitamins and carotenoid status. PMID:15070410

  17. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation.

    PubMed

    Stong, Rachel A; Kolodny, Eli; Kelsey, Rick G; González-Hernández, M P; Vivanco, Jorge M; Manter, Daniel K

    2013-06-01

    Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon white oak) in order to evaluate the effect of differing sterol/tannin contents on Phytophthora ramorum growth. For all three species, high levels of foliage inhibited P. ramorum growth and sporulation, with a steeper concentration dependence for the two oak samples. Phytophthora ramorum growth and sporulation were inhibited by either phytosterols or tannin-enriched extracts. High levels of sterols diminished elicitin gene expression in P. ramorum; whereas the tannin-enriched extract decreased the amount of 'functional' or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, P. ramorum growth and sporulation correlated strongly with the amount of ELISA-detectable elicitin (R (2) = 0.791 and 0.961, respectively).

  18. Osh4p exchanges sterols for phosphatidylinositol 4-phosphate between lipid bilayers

    PubMed Central

    de Saint-Jean, Maud; Delfosse, Vanessa; Douguet, Dominique; Chicanne, Gaëtan; Payrastre, Bernard; Bourguet, William

    2011-01-01

    Osh/Orp proteins transport sterols between organelles and are involved in phosphoinositide metabolism. The link between these two aspects remains elusive. Using novel assays, we address the influence of membrane composition on the ability of Osh4p/Kes1p to extract, deliver, or transport dehydroergosterol (DHE). Surprisingly, phosphatidylinositol 4-phosphate (PI(4)P) specifically inhibited DHE extraction because PI(4)P was itself efficiently extracted by Osh4p. We solve the structure of the Osh4p–PI(4)P complex and reveal how Osh4p selectively substitutes PI(4)P for sterol. Last, we show that Osh4p quickly exchanges DHE for PI(4)P and, thereby, can transport these two lipids between membranes along opposite routes. These results suggest a model in which Osh4p transports sterol from the ER to late compartments pinpointed by PI(4)P and, in turn, transports PI(4)P backward. Coupled to PI(4)P metabolism, this transport cycle would create sterol gradients. Because the residues that recognize PI(4)P are conserved in Osh4p homologues, other Osh/Orp are potential sterol/phosphoinositol phosphate exchangers. PMID:22162133

  19. Crystal structure of the human sterol transporter ABCG5/ABCG8

    PubMed Central

    Lee, Jyh-Yeuan; Kinch, Lisa N.; Borek, Dominika M.; Wang, Jin; Wang, Junmei; Urbatsch, Ina L.; Xie, Xiao-Song; Grishin, Nikolai V.; Cohen, Jonathan C.; Otwinowski, Zbyszek; Hobbs, Helen H.; Rosenbaum, Daniel M.

    2016-01-01

    ATP binding cassette (ABC) transporters play critical roles in maintaining sterol balance in higher eukaryotes. The ABCG5/ABCG8 heterodimer (G5G8) mediates excretion of neutral sterols in liver and intestines1–5. Mutations disrupting G5G8 cause sitosterolaemia, a disorder characterized by sterol accumulation and premature atherosclerosis. Here we use crystallization in lipid bilayers to determine the X-ray structure of human G5G8 in a nucleotide-free state at 3.9 Å resolution, generating the first atomic model of an ABC sterol transporter. The structure reveals a new transmembrane fold that is present in a large and functionally diverse superfamily of ABC transporters. The transmembrane domains are coupled to the nucleotide-binding sites by networks of interactions that differ between the active and inactive ATPases, reflecting the catalytic asymmetry of the transporter. The G5G8 structure provides a mechanistic framework for understanding sterol transport and the disruptive effects of mutations causing sitosterolaemia. PMID:27144356

  20. Regulation of Squalene Synthase, a Key Enzyme of Sterol Biosynthesis, in Tobacco1

    PubMed Central

    Devarenne, Timothy P.; Ghosh, Anirban; Chappell, Joe

    2002-01-01

    Squalene synthase (SS) represents a putative branch point in the isoprenoid biosynthetic pathway capable of diverting carbon flow specifically to the biosynthesis of sterols and, hence, is considered a potential regulatory point for sterol metabolism. For example, when plant cells grown in suspension culture are challenged with fungal elicitors, suppression of sterol biosynthesis has been correlated with a reduction in SS enzyme activity. The current study sought to correlate changes in SS enzyme activity with changes in the level of the corresponding protein and mRNA. Using an SS-specific antibody, the initial suppression of SS enzyme activity in elicitor-challenged cells was not reflected by changes in the absolute level of the corresponding polypeptide, implicating a post-translational control mechanism for this enzyme activity. In comparison, the absolute level of the SS mRNA did decrease approximately 5-fold in the elicitor-treated cells, which is suggestive of decreased transcription of the SS gene. Study of SS in intact plants was also initiated by measuring the level of SS enzyme activity, the level of the corresponding protein, and the expression of SS gene promoter-reporter gene constructs in transgenic plants. SS enzyme activity, polypeptide level, and gene expression were all localized predominately to the shoot apical meristem, with much lower levels observed in leaves and roots. These later results suggest that sterol biosynthesis is localized to the apical meristems and that apical meristems may be a source of sterols for other plant tissues. PMID:12114564

  1. Analysis of Vascular Development in the hydra Sterol Biosynthetic Mutants of Arabidopsis

    PubMed Central

    Pullen, Margaret; Clark, Nick; Zarinkamar, Fatemeh; Topping, Jennifer; Lindsey, Keith

    2010-01-01

    Background The control of vascular tissue development in plants is influenced by diverse hormonal signals, but their interactions during this process are not well understood. Wild-type sterol profiles are essential for growth, tissue patterning and signalling processes in plant development, and are required for regulated vascular patterning. Methodology/Principal Findings Here we investigate the roles of sterols in vascular tissue development, through an analysis of the Arabidopsis mutants hydra1 and fackel/hydra2, which are defective in the enzymes sterol isomerase and sterol C-14 reductase respectively. We show that defective vascular patterning in the shoot is associated with ectopic cell divisions. Expression of the auxin-regulated AtHB8 homeobox gene is disrupted in mutant embryos and seedlings, associated with variably incomplete vascular strand formation and duplication of the longitudinal axis. Misexpression of the auxin reporter proIAA2∶GUS and mislocalization of PIN proteins occurs in the mutants. Introduction of the ethylene-insensitive ein2 mutation partially rescues defective cell division, localization of PIN proteins, and vascular strand development. Conclusions The results support a model in which sterols are required for correct auxin and ethylene crosstalk to regulate PIN localization, auxin distribution and AtHB8 expression, necessary for correct vascular development. PMID:20808926

  2. Sterol biosynthesis via cycloartenol and other biochemical features related to photosynthetic phyla in the amoeba Naegleria lovaniensis and Naegleria gruberi.

    PubMed

    Raederstorff, D; Rohmer, M

    1987-04-15

    The sterols and sterol precursors of two amoebae of the genus Naegleria, Naegleria lovaniensis and Naegleria gruberi were investigated. Cycloartenol, the sterol precursor in photosynthetic organisms, is present in both amoebae. In N. lovaniesis, it is accompanied by lanosterol and parkeol, as well as by the 24,25-dihydro derivatives of these triterpenes. One of the most striking features of these amoebae is the accumulation of 4 alpha-methylsterols which are present in similar amounts as those of 4,4-desmethylsterols (3-5 mg/g, dry weight). 4 alpha-Methylergosta-7,22-dienol was identified as a new compound. Ergosterol was the major 4,4-desmethylsterol, accompanied by small amounts of C27 and other C28 sterols. Treatment of N. lovaniensis with fenpropimorph modified the sterol pattern of this amoeba and inhibited its growth. This fungicide, known to inhibit steps of sterol biosynthesis in fungi and plants, induced the disappearance of 4 alpha-methyl-delta 7-sterols and the appearance of the unusual delta 6,8,22-ergostatrienol as in A. polyphaga. These results might be explained by a partial inhibition of the delta 8----delta 7 isomerase, the small amounts of delta 7-sterols formed being converted into ergosterol which is still present in fenpropimorph-exposed cells. De novo sterol biosynthesis in N. lovaniensis was shown by incorporation of [1-14C]acetate into sterols and sterol precursors, especially cycloartenol. Lanosterol and parkeol were not significantly labelled. Furthermore, [3-3H]squalene epoxide was efficiently cyclized by a cell-free system of this amoeba into cycloartenol, and again no significant radioactivity was detected in lanosterol and parkeol. This shows that cycloartenol, the sterol precursor in plants and algae, is also the sterol precursor in Naegleria species, and that these amoebae, like A. polyphaga, are related by some biosynthetic pathways to photosynthetic phyla. Lanosterol, the sterol precursor in non-photosynthetic phyla (animal and

  3. Expression and properties of three novel fungal lipases/sterol esterases predicted in silico: comparison with other enzymes of the Candida rugosa-like family.

    PubMed

    Vaquero, María Eugenia; Prieto, Alicia; Barriuso, Jorge; Martínez, María Jesús

    2015-12-01

    Lipases from the Candida rugosa-like family are enzymes with great biotechnological interest. In a previous work, several enzymes from this family were identified by in silico mining of fungal genomes. Here, we describe the cloning, expression, and characterization of putative lipases from the genomes of Nectria haematococca, Trichoderma reesei, and Aspergillus niger and compared their catalytic properties with those of OPE, a well-characterized sterol esterase/lipase from Ophiostoma piceae. All of them hydrolyzed p-nitrophenol esters and triglycerides with different efficiency, but their activity against sterol esters was dissimilar, and the enzyme from A. niger was unable of hydrolyzing these substrates while OPE showed the best k cat values, which in general leads to an improved catalytic efficiency. Similarly, OPE was the best catalyst in the synthesis of β-sitostanyl oleate, followed by the commercial CRL from C. rugosa, while the A. niger enzyme was unable to produce this compound. When the enzymes were evaluated for caprolactone oligomerization, the A. niger enzyme gave similar results than CRL, being OPE slightly more efficient. The expression of the putative selected proteins allowed their functional validation, suggesting that the hydrophobicity of the lid region may be an important factor, although the enzymatic efficiency is also influenced by other parameters, as the aggregation state and the size and morphology of the tunnel, where substrate recognition and catalysis takes place.

  4. Distribution of sterol carrier protein/sub 2/ (SCP/sub 2/) in rat tissues and evidence for slow turnover in liver and adrenal cortex

    SciTech Connect

    Kharroubi, A., Chanderbhan, R.; Fiskum, G.; Noland, B.J.; Scallen, T.J.; Vahouny, G.V.

    1986-03-05

    Sterol carrier protein/sub 2/ (SCP/sub 2/) has been implicated in the regulation of the terminal stages of hepatic cholesterol biosynthesis, and in sterol utilization for adrenal steroid hormone and hepatic bile acid synthesis. In the present studies, a highly sensitive radioimmunoassay, using (/sup 125/I) SCP/sub 2/, has been developed. Highest levels of SCP/sub 2/ were found in rat liver with progressively lower levels in intestinal mucosa, adrenal, kidney, lung and testis. SCP/sub 2/ levels were low or absent in heart, brain, skeletal muscle and serum. Liver SCP/sub 2/ was largely (44%) associated with the microsomal fraction, while in adrenal, 46% was associated with mitochondria, a distribution which is consistent with the proposed roles for SCP/sub 2/ in these tissues. Levels of SCP/sub 2/ in AS 30D hepatoma cells were only 5% of those in normal liver. In liver there was no indication of diurnal rhythm of SCP/sub 2/ in the cytosol and only slight variation of the microsomal SCP/sub 2/ levels. Fasting has only slight effects on SCP/sub 2/ concentration of rat liver microsomes and cytosol. Neither ACTH nor cycloheximide treatment of rats had a significant effect on SCP/sub 2/ distribution in the adrenal. In general, these findings indicate that SCP/sub 2/ has a low turn-over rate.

  5. Relation of acidity and sensory quality with sterol content of olive oil from stored fruit.

    PubMed

    Gutiérrez, F; Varona, I; Albi, M A

    2000-04-01

    Composition of the sterol fraction, fatty acid, acidity, and the sensorial evaluation of virgin olive oils were studied in two eastern Spanish varieties grown and processed under the same conditions. Fruits were stored at 5 degrees C and ambient temperature for different times. During fruit storage, there was no significant variation (P = 0.05) in fatty acid composition. However, the sterol composition of the oil varied markedly (in particular, there was an increase in stigmasterol), acidity increased, and there was a very significant decrease in sensorial quality. The stigmasterol content presented a high correlation with the acidity and sensory evaluation (P < 10(-)(6)). The total sterol content increased gradually with olive storage time. Oils with stigmasterol greater than campesterol are graded to a low level (lampant). It is of interest that sensorial quality is revealed by stigmasterol content, a fact unknown until now.

  6. Plant sterols as anticancer nutrients: evidence for their role in breast cancer.

    PubMed

    Grattan, Bruce J

    2013-01-31

    While many factors are involved in the etiology of cancer, it has been clearly established that diet significantly impacts one's risk for this disease. More recently, specific food components have been identified which are uniquely beneficial in mitigating the risk of specific cancer subtypes. Plant sterols are well known for their effects on blood cholesterol levels, however research into their potential role in mitigating cancer risk remains in its infancy. As outlined in this review, the cholesterol modulating actions of plant sterols may overlap with their anti-cancer actions. Breast cancer is the most common malignancy affecting women and there remains a need for effective adjuvant therapies for this disease, for which plant sterols may play a distinctive role.

  7. Novel sterol glucosyltransferase in the animal tissue and cultured cells: evidence that glucosylceramide as glucose donor.

    PubMed

    Akiyama, Hisako; Sasaki, Narie; Hanazawa, Shuwa; Gotoh, Mari; Kobayashi, Susumu; Hirabayashi, Yoshio; Murakami-Murofushi, Kimiko

    2011-05-01

    Cholesteryl glucoside (CG), a membrane glycolipid, regulates heat shock response. CG is rapidly induced by heat shock before the activation of heat shock transcription factor 1 (HSF1) and production of heat shock protein 70 (HSP70), and the addition of CG in turn induces HSF1 activation and HSP70 production in human fibroblasts; thus, a reasonable correlation is that CG functions as a crucial lipid mediator in stress responses in the animal. In this study, we focused on a CG-synthesizing enzyme, animal sterol glucosyltransferase, which has not yet been identified. In this study, we describe a novel type of animal sterol glucosyltransferase in hog stomach and human fibroblasts (TIG-3) detected by a sensitive assay with a fluorescence-labeled substrate. The cationic requirement, inhibitor resistance, and substrate specificity of animal sterol glucosyltransferase were studied. Interestingly, animal sterol glucosyltransferase did not use uridine diphosphate glucose (UDP-glucose) as an immediate glucose donor, as has been shown in plants and fungi. Among the glycolipids tested in vitro, glucosylceramide (GlcCer) was the most effective substrate for CG formation in animal tissues and cultured cells. Using chemically synthesized [U-((13))C]Glc-β-Cer as a glucose donor, we confirmed by mass spectrometry that [U-((13))C]CG was synthesized in hog stomach homogenate. These results suggest that animal sterol glucosyltransferase transfers glucose moiety from GlcCer to cholesterol. Additionally, using GM-95, a mutant B16 melanoma cell line that does not express ceramide glucosyltransferase, we showed that GlcCer is an essential substrate for animal sterol glucosyltransferase in the cell.

  8. Cerebral accumulation of dietary derivable plant sterols does not interfere with memory and anxiety related behavior in Abcg5-/- mice.

    PubMed

    Vanmierlo, Tim; Rutten, Kris; van Vark-van der Zee, Leonie C; Friedrichs, Silvia; Bloks, Vincent W; Blokland, Arjan; Ramaekers, Frans C; Sijbrands, Eric; Steinbusch, Harry; Prickaerts, Jos; Kuipers, Folkert; Lütjohann, Dieter; Mulder, Monique

    2011-06-01

    Plant sterols such as sitosterol and campesterol are frequently applied as functional food in the prevention of atherosclerosis. Recently, it became clear that plasma derived plant sterols accumulate in murine brains. We questioned whether plant sterols in the brain are associated with alterations in brain cholesterol homeostasis and subsequently with brain functions. ATP binding cassette (Abc)g5-/- mice, a phytosterolemia model, were compared to Abcg5+/+ mice for serum and brain plant sterol accumulation and behavioral and cognitive performance. Serum and brain plant sterol concentrations were respectively 35-70-fold and 5-12-fold increased in Abcg5-/- mice (P<0.001). Plant sterol accumulation resulted in decreased levels of desmosterol (P<0.01) and 24(S)-hydroxycholesterol (P<0.01) in the hippocampus, the brain region important for learning and memory functions, and increased lanosterol levels (P<0.01) in the cortex. However, Abcg5-/- and Abcg5+/+ displayed no differences in memory functions or in anxiety and mood related behavior. The swimming speed of the Abcg5-/- mice was slightly higher compared to Abcg5+/+ mice (P<0.001). In conclusion, plant sterols in the brains of Abcg5-/- mice did have consequences for brain cholesterol metabolism, but did not lead to an overt phenotype of memory or anxiety related behavior. Thus, our data provide no contra-indication for nutritional intake of plant sterol enriched nutrition.

  9. Sterol Composition and Ecdysteroid Content of Eggs of the Root-knot Nematodes Meloidogyne incognita and M. arenaria

    PubMed Central

    Chitwood, David J.; McClure, Michael A.; Feldlaufer, Mark F.; Lusby, William R.; Oliver, Tames E.

    1987-01-01

    Free and esterified sterols of eggs of the root-knot nematodes Meloidogyne incognita races 2 and 3 and M. arenaria race 1 were isolated and identified by gas-liquid chromatography-mass spectrometry. The major sterols of eggs of each race were 24-ethylcholesterol (33.4-38.8% of total sterol), 24-ethylcholestanol (18.3-25.3%), 24-methylcholesterol (8.6-11.7%), 24-methylcholestanol (7.7-12.5%), and cholesterol (4.6-11.6%). Consequently, the major metabolic transformation performed by Meloidogyne females or eggs upon host sterols appeared to be saturation of the sterol nucleus. The free and esterified sterols of the same race did not differ appreciably, except for a slight enrichment of the steryl esters in cholesterol. Although the sterol composition of Meloidogyne eggs differed from that of other life stages of other genera of plant-parasitic nematodes, the three Meloidogyne races could not be distinguished from each other by their egg sterols. Ecdysteroids, compounds with hormonal function in insects, were not detected by radioimmunoassay in the Meloidogyne eggs either as free ecdysteroids or as polar conjugates. PMID:19290155

  10. Potential of the desert locust schistocerca gregaria (Orthoptera: Acrididae) as an unconventional source of dietary and therapeutic sterols

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insects are increasingly being recognized not only as a source of food to feed the ever growing world population but also as potential sources of new products and therapeutic agents, among which are sterols. In this study, we sought to profile sterols and their derivatives present in the desert locu...

  11. Concentrations of surfactants and sterols in the surface microlayer of the estuarine areas of Selangor River, Malaysia

    NASA Astrophysics Data System (ADS)

    Alsalahi, Murad Ali; Talib Latif, Mohd; Mohd Ali, Masni; Dominick, Doreena; Firoz Khan, Md; Bahiyah Abd Wahid, Nurul; Ili Hamizah Mustaffa, Nur

    2016-04-01

    This study determined the concentration of surfactant and sterols as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. SML samples were collected during different seasons using a rotation drum method. The compositions of surfactants in SML were determined as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS) as anionic and cationic surfactants respectively. The concentration of sterols was determined using a gas chromatography equipped with a flame ionisation detector (GC-FID). The results show that the concentrations of surfactants around the estuarine area were dominated by anionic surfactants (MBAS) with average concentrations of 0.39 μmol L-1. The concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L-1. The surfactants and total sterol concentrations were found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML of the Selangor River. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%).

  12. Plant sterols and their role in combined use with statins for lipid lowering.

    PubMed

    Normén, Lena; Holmes, Daniel; Frohlich, Jiri

    2005-03-01

    Cardiovascular disease (CVD) is currently one of the major contributors to the global burden of disease. Combination treatments to promote a maximal reduction of the ratio between total cholesterol and high-density lipoprotein are currently the most effective way of preventing CVD. In this review, we assess the role of plant sterols and statins in CVD prevention. Statins have been used by millions of patients at high to moderate risk of CVD, while plant sterols are potentially available to whole populations in food products. The benefits and risks of each compound, as well as the combination, are discussed.

  13. Silicon Incorporated Morpholine Antifungals: Design, Synthesis, and Biological Evaluation

    PubMed Central

    2015-01-01

    Known morpholine class antifungals (fenpropimorph, fenpropidin, and amorolfine) were synthetically modified through silicon incorporation to have 15 sila-analogues. Twelve sila-analogues exhibited potent antifungal activity against different human fungal pathogens such as Candida albicans, Candida glabrata, Candida tropicalis, Cryptococcus neoformans, and Aspergillus niger. Sila-analogue 24 (fenpropimorph analogue) was the best in our hands, which showed superior fungicidal potential than fenpropidin, fenpropimorph, and amorolfine. The mode of action of sila-analogues was similar to morpholines, i.e., inhibition of sterol reductase and sterol isomerase enzymes of ergosterol synthesis pathway. PMID:26617963

  14. Synthesis of 1 nm Pd Nanoparticles in a Microfluidic Reactor: Insights from in Situ X ray Absorption Fine Structure Spectroscopy and Small-Angle X ray Scattering

    SciTech Connect

    Karim, Ayman M.; Al Hasan, Naila M.; Ivanov, Sergei A.; Siefert, Soenke; Kelly, Ryan T.; Hallfors, Nicholas G.; Benavidez, Angelica D.; Kovarik, Libor; Jenkins, Aaron; Winans, R. E.; Datye, Abhaya K.

    2015-06-11

    In this paper we show that the temporal separation of nucleation and growth is not a necessary condition for the colloidal synthesis of monodisperse nanoparticles. The synthesis mechanism of Pd nanoparticles was determined by in situ XAFS and SAXS in a microfluidic reactor capable of millisecond up to an hour time resolution. The SAXS results showed two autocatalytic growth phases, a fast growth phase followed by a very slow growth phase. The steady increase in the number of particles throughout the two growth phases indicates the synthesis is limited by slow continuous nucleation. The transition from fast to slow growth was caused by rapid increase in bonding with the capping agent as shown by XAFS. Based on this fundamental understanding of the synthesis mechanism, we show that 1 nm monodisperse Pd nanoparticles can be synthesized at low temperature using a strong binding capping agent such as trioctylphosphine (TOP).

  15. Cholesterol absorption and synthesis markers in individuals with and without a CHD event during pravastatin therapy: insights from the PROSPER trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cholesterol homeostasis, defined as the balance between absorption and synthesis, influences circulating cholesterol concentrations and subsequent coronary heart disease (CHD) risk. Statin therapy targets the rate-limiting enzyme in cholesterol biosynthesis and is efficacious in lowering CHD events ...

  16. Sterol chemical configuration influences the thermotropic phase behaviour of dipalmitoylphosphatidylcholine bilayers containing 5α-cholestan-3β- and 3α-ol.

    PubMed

    Benesch, Matthew G K; Mannock, David A; McElhaney, Ronald N

    2011-01-01

    It is commonly believed that all membrane sterols are rigid all-trans ring systems with a fully extended alkyl side-chain and that they similarly influence phospholipid bilayer physical properties. Here, we report the sterol concentration-dependent, thermotropic phase behaviour of binary dipalmitoylphosphatidylcholine (DPPC)/sterol mixtures containing two similar 5α-H sterols with different functional group orientations (3α-OH or 3β-OH), which adopt an ideal all-trans planar ring conformation but lack the deformed ring B conformation of cholesterol (Chol) and epicholesterol (Echol), using differential scanning calorimetry (DSC). Our deconvolution of the DSC main phase transition endotherms show differences in the proportions of sterol-poor (sharp) and sterol-rich (broad) domains in the DPPC bilayer with increasing sterol concentration, which delineate gel/liquid-crystalline (P(β')/L(α)) and disordered gel (L(β))/liquid-ordered (l(o)) phase regions. There are similarities in the DPPC main phase transition temperature, cooperativity and enthalpy for each 3β-ol and 3α-ol pair with increasing sterol concentration and differences in the parameters obtained for both the sterol-poor and sterol-rich regions. The sterol-poor domain persists over a greater concentration range in both 3α-ol/DPPC mixtures, suggesting that either those domains are more stable in the 3α-ols or that those sterols are less miscible in the sterol-rich domain. Corresponding parameters for the sterol-rich domain show that at sterol concentrations up to 20mol%, the 5α-H,3β-ol is more effective at reducing the phase transition enthalpy of the broad component (ΔH(m)(brd)) than Chol, but is less effective at higher concentrations. Although mixtures containing Echol and 5α-cholestan-3α-ol have similar positive slopes below 7mol% sterol, suggesting that they abolish the L(β)/l(o) phase transition equally effectively at low concentrations, Echol is more effective than the saturated 3α-ol at

  17. Evidence for a role of sterol 27-hydroxylase in glucocorticoid metabolism in vivo.

    PubMed

    Vögeli, Isabelle; Jung, Hans H; Dick, Bernhard; Erickson, Sandra K; Escher, Robert; Funder, John W; Frey, Felix J; Escher, Geneviève

    2013-11-01

    The intracellular availability of glucocorticoids is regulated by the enzymes 11β-hydroxysteroid dehydrogenase 1 (HSD11B1) and 11β-hydroxysteroid dehydrogenase 2 (HSD11B2). The activity of HSD11B1 is measured in the urine based on the (tetrahydrocortisol+5α-tetrahydrocortisol)/tetrahydrocortisone ((THF+5α-THF)/THE) ratio in humans and the (tetrahydrocorticosterone+5α-tetrahydrocorticosterone)/tetrahydrodehydrocorticosterone ((THB+5α-THB)/THA) ratio in mice. The cortisol/cortisone (F/E) ratio in humans and the corticosterone/11-dehydrocorticosterone (B/A) ratio in mice are markers of the activity of HSD11B2. In vitro agonist treatment of liver X receptor (LXR) down-regulates the activity of HSD11B1. Sterol 27-hydroxylase (CYP27A1) catalyses the first step in the alternative pathway of bile acid synthesis by hydroxylating cholesterol to 27-hydroxycholesterol (27-OHC). Since 27-OHC is a natural ligand for LXR, we hypothesised that CYP27A1 deficiency may up-regulate the activity of HSD11B1. In a patient with cerebrotendinous xanthomatosis carrying a loss-of-function mutation in CYP27A1, the plasma concentrations of 27-OHC were dramatically reduced (3.8 vs 90-140 ng/ml in healthy controls) and the urinary ratios of (THF+5α-THF)/THE and F/E were increased, demonstrating enhanced HSD11B1 and diminished HSD11B2 activities. Similarly, in Cyp27a1 knockout (KO) mice, the plasma concentrations of 27-OHC were undetectable (<1 vs 25-120 ng/ml in Cyp27a1 WT mice). The urinary ratio of (THB+5α-THB)/THA was fourfold and that of B/A was twofold higher in KO mice than in their WT littermates. The (THB+5α-THB)/THA ratio was also significantly increased in the plasma, liver and kidney of KO mice. In the liver of these mice, the increase in the concentrations of active glucocorticoids was due to increased liver weight as a consequence of Cyp27a1 deficiency. In vitro, 27-OHC acts as an inhibitor of the activity of HSD11B1. Our studies suggest that the expression of CYP27A1

  18. Sterol carrier protein 2 regulates proximal tubule size in the Xenopus pronephric kidney by modulating lipid rafts.

    PubMed

    Cerqueira, Débora M; Tran, Uyen; Romaker, Daniel; Abreu, José G; Wessely, Oliver

    2014-10-01

    The kidney is a homeostatic organ required for waste excretion and reabsorption of water, salts and other macromolecules. To this end, a complex series of developmental steps ensures the formation of a correctly patterned and properly proportioned organ. While previous studies have mainly focused on the individual signaling pathways, the formation of higher order receptor complexes in lipid rafts is an equally important aspect. These membrane platforms are characterized by differences in local lipid and protein compositions. Indeed, the cells in the Xenopus pronephric kidney were positive for the lipid raft markers ganglioside GM1 and Caveolin-1. To specifically interfere with lipid raft function in vivo, we focused on the Sterol Carrier Protein 2 (scp2), a multifunctional protein that is an important player in remodeling lipid raft composition. In Xenopus, scp2 mRNA was strongly expressed in differentiated epithelial structures of the pronephric kidney. Knockdown of scp2 did not interfere with the patterning of the kidney along its proximo-distal axis, but dramatically decreased the size of the kidney, in particular the proximal tubules. This phenotype was accompanied by a reduction of lipid rafts, but was independent of the peroxisomal or transcriptional activities of scp2. Finally, disrupting lipid micro-domains by inhibiting cholesterol synthesis using Mevinolin phenocopied the defects seen in scp2 morphants. Together these data underscore the importance for localized signaling platforms in the proper formation of the Xenopus kidney.

  19. Gentiana manshurica Kitagawa reverses acute alcohol-induced liver steatosis through blocking sterol regulatory element-binding protein-1 maturation.

    PubMed

    Lian, Li-Hua; Wu, Yan-Ling; Song, Shun-Zong; Wan, Ying; Xie, Wen-Xue; Li, Xin; Bai, Ting; Ouyang, Bing-Qing; Nan, Ji-Xing

    2010-12-22

    This study was undertaken to investigate the protective effects of Gentiana manshurica Kitagawa (GM) on acute alcohol-induced fatty liver. Mice were treated with ethanol (5 g/kg of body weight) by gavage every 12 h for a total of three doses to induce acute fatty liver. Methanol extract of GM (50, 100, or 200 mg/kg) or silymarin (100 mg/kg) was gavaged simultaneously with ethanol for three doses. GM administration significantly reduced the increases in serum ALT and AST levels, the serum and hepatic triglyceride levels, at 4 h after the last ethanol administration. GM was also found to prevent ethanol-induced hepatic steatosis and necrosis, as indicated by liver histopathological studies. Additionally, GM suppressed the elevation of malondialdehyde (MDA) levels, restored the glutathione (GSH) levels, and enhanced the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. The concurrent administration of GM efficaciously abrogated cytochrome P450 2E1 (CYP2E1) induction. Moreover, GM significantly reduced the nuclear translocation of sterol regulatory element-binding protein-1 (nSREBP-1) in ethanol-treated mice. These data indicated that GM possessed the ability to prevent ethanol-induced acute liver steatosis, possibly through blocking CYP2E1-mediated free radical scavenging effects and SREBP-1-regulated fatty acid synthesis. Especially, GM may be developed as a potential therapeutic candidate for ethanol-induced oxidative damage in liver.

  20. C-24 Stereochemistry of Marine Sterols: (22E)-25,28-Dimethyl- stigmasta-5,22,28-trien-3β-ol and 25,28-Dimethylstigmasta-5,28-dien-3β-ol.

    PubMed

    Nojo, Rie; Echigo, Shizue; Hara, Noriyuki; Fujimoto, Yoshinori

    2014-12-01

    The C-24 configurations of (22E)-25,28-dimethylstigmasta-5,22,28-trien-3β-ol (1) and 25,28-dimethylstigmasta-5,28-dien-3β-ol (2), isolated from the sponge Topsentia ophiraphidites in our previous work, were determined to be both S, through the synthesis of stereodefined (24S)- and (24R)-epimers of 1 and 2 and comparison of the 1H and 13C NMR spectroscopic data. In addition, the C-24 configurations of the marine sterols having the same structures as 1 and 2 and their derivatives were also assigned for the first time by NMR comparison.

  1. In vivo promoter analysis on refeeding response of hepatic sterol regulatory element-binding protein-1c expression

    SciTech Connect

    Takeuchi, Yoshinori; Yahagi, Naoya; Nakagawa, Yoshimi; Matsuzaka, Takashi; Shimizu, Ritsuko; Sekiya, Motohiro; Iizuka, Yoko; Ohashi, Ken; Gotoda, Takanari; Yamamoto, Masayuki; Nagai, Ryozo; Kadowaki, Takashi; Yamada, Nobuhiro; Osuga, Jun-ichi; Shimano, Hitoshi

    2007-11-16

    Sterol regulatory element-binding protein (SREBP)-1c is the master regulator of lipogenic gene expression in liver. The mRNA abundance of SREBP-1c is markedly induced when animals are refed after starvation, although the regulatory mechanism is so far unknown. To investigate the mechanism of refeeding response of SREBP-1c gene expression in vivo, we generated a transgenic mouse model that carries 2.2 kb promoter region fused to the luciferase reporter gene. These transgenic mice exhibited refeeding responses of the reporter in liver and adipose tissues with extents essentially identical to those of endogenous SREBP-1c mRNA. The same results were obtained from experiments using adenovirus-mediated SREBP-1c-promoter-luciferase fusion gene transduction to liver. These data demonstrate that the regulation of SREBP-1c gene expression is at the transcription level, and that the 2.2 kb 5'-flanking region is sufficient for this regulation. Moreover, when these transgenic or adenovirus-infected mice were placed on insulin-depleted state by streptozotocin treatment, the reporter expression was upregulated as strongly as in control mice, demonstrating that this regulation is not dominated by serum insulin level. These mice are the first models to provide the mechanistic insight into the transcriptional regulation of SREBP-1c gene in vivo.

  2. Sterols from Thai Marine Sponge Petrosia (Strongylophora) sp. and Their Cytotoxicity

    PubMed Central

    Pailee, Phanruethai; Mahidol, Chulabhorn; Ruchirawat, Somsak; Prachyawarakorn, Vilailak

    2017-01-01

    Eight new sterols (1–5 and 11–13), together with eight known compounds (6–10 and 14–16) were isolated from marine sponge Petrosia sp. The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis. The cytotoxicity of some compounds against a panel of human cancer cell lines is also reported. PMID:28241489

  3. Plant sterol consumption frequency affects plasma lipid levels and cholesterol kinetics in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background/Objectives: To compare the efficacy of single versus multiple doses of plant sterols on circulating lipid level and cholesterol trafficking. Subjects/Methods: A randomized, placebo-controlled, three-phase (6 days/phase) crossover, supervised feeding trial was conducted in 19 subjects. Sub...

  4. Chromatic aberration correction and deconvolution for UV sensitive imaging of fluorescent sterols in cytoplasmic lipid droplets.

    PubMed

    Wüstner, Daniel; Faergeman, Nils J

    2008-08-01

    Intrinsically fluorescent sterols, like dehydroergosterol (DHE), mimic cholesterol closely and are therefore suitable to determine cholesterol transport by fluorescence microscopy. Disadvantages of DHE are its low quantum yield, rapid bleaching, and the fact that its excitation and emission is in the UV region of the spectrum. Thus, one has to deal with chromatic aberration and low signal-to-noise ratio. We developed a method to correct for chromatic aberration between the UV channel and the red/green channel in multicolor imaging of DHE compared with the lipid droplet marker Nile Red in living macrophage foam cells and in adipocytes. We used deconvolution microscopy and developed image segmentation techniques to assess the DHE content of lipid droplets in both cell types in an automated manner. Pulse-chase studies and colocalization analysis were performed to monitor the redistribution of DHE upon adipocyte differentiation. DHE is targeted to transferrin-positive recycling endosomes in preadipocytes but associates with droplets in mature adipocytes. Only in adipocytes but not in foam cells fluorescent sterol was confined to the droplet-limiting membrane. We developed an approach to visualize and quantify sterol content of lipid droplets in living cells with potential for automated high content screening of cellular sterol transport.

  5. Type I diabetes mellitus decreases in vivo macrophage-to-feces reverse cholesterol transport despite increased biliary sterol secretion in mice

    PubMed Central

    Freark de Boer, Jan; Annema, Wijtske; Schreurs, Marijke; van der Veen, Jelske N.; van der Giet, Markus; Nijstad, Niels; Kuipers, Folkert; Tietge, Uwe J. F.

    2012-01-01

    Type I diabetes mellitus (T1DM) increases atherosclerotic cardiovascular disease; however, the underlying pathophysiology is still incompletely understood. We investigated whether experimental T1DM impacts HDL-mediated reverse cholesterol transport (RCT). C57BL/6J mice with alloxan-induced T1DM had higher plasma cholesterol levels (P < 0.05), particularly within HDL, and increased hepatic cholesterol content (P < 0.001). T1DM resulted in increased bile flow (2.1-fold; P < 0.05) and biliary secretion of bile acids (BA, 10.5-fold; P < 0.001), phospholipids (4.5-fold; P < 0.001), and cholesterol (5.5-fold; P < 0.05). Hepatic cholesterol synthesis was unaltered, whereas BA synthesis was increased in T1DM (P < 0.001). Mass fecal BA output was significantly higher in T1DM mice (1.5-fold; P < 0.05), fecal neutral sterol excretion did not change due to increased intestinal cholesterol absorption (2.1-fold; P < 0.05). Overall in vivo macrophage-to-feces RCT, using [3H]cholesterol-loaded primary mouse macrophage foam cells, was 20% lower in T1DM (P < 0.05), mainly due to reduced tracer excretion within BA (P < 0.05). In vitro experiments revealed unchanged cholesterol efflux toward T1DM HDL, whereas scavenger receptor class BI-mediated selective uptake from T1DM HDL was lower in vitro and in vivo (HDL kinetic experiments) (P < 0.05), conceivably due to increased glycation of HDL-associated proteins (+65%, P < 0.01). In summary, despite higher mass biliary sterol secretion T1DM impairs macrophage-to-feces RCT, mainly by decreasing hepatic selective uptake, a mechanism conceivably contributing to increased cardiovascular disease in T1DM. PMID:22180634

  6. Tomatidine promotes the inhibition of 24-alkylated sterol biosynthesis and mitochondrial dysfunction in Leishmania amazonensis promastigotes.

    PubMed

    Medina, J M; Rodrigues, J C F; De Souza, W; Atella, G C; Barrabin, H

    2012-09-01

    Leishmaniasis is a set of clinically distinct infectious diseases caused by Leishmania, a genus of flagellated protozoan parasites, that affects ~12 million people worldwide, with ~2 million new infections annually. Plants are known to produce substances to defend themselves against pathogens and predators. In the genus Lycopersicon, which includes the tomato, L. esculentum, the main antimicrobial compound is the steroidal glycoalkaloid α-tomatine. The loss of the saccharide side-chain of tomatine yields the aglycone tomatidine. In the present study, we investigated the effects of tomatidine on the growth, mitochondrial membrane potential, sterol metabolism, and ultrastructure of Leishmania amazonensis promastigotes. Tomatidine (0·1 to 5 μM) inhibited parasite growth in a dose-dependent manner (IC(50)=124±59 nM). Transmission electron microscopy revealed lesions in the mitochondrial ultrastructure and the presence of large vacuoles and lipid storage bodies in the cytoplasm. These structural changes in the mitochondria were accompanied by an effective loss of mitochondrial membrane potential and a decrease in ATP levels. An analysis of the neutral lipid content revealed a large depletion of endogenous 24-alkylated sterols such as 24-methylene-cholesta-5, 7-dien-3β-ol (5-dehydroepisterol), with a concomitant accumulation of cholesta-8, 24-dien-3β-ol (zymosterol), which implied a perturbation in the cellular lipid content. These results are consistent with an inhibition of 24-sterol methyltransferase, an important enzyme responsible for the methylation of sterols at the 24 position, which is an essential step in the production of ergosterol and other 24-methyl sterols.

  7. Trypanosoma cruzi Response to Sterol Biosynthesis Inhibitors: Morphophysiological Alterations Leading to Cell Death

    PubMed Central

    Kessler, Rafael Luis; Soares, Maurilio José; Probst, Christian Macagnan; Krieger, Marco Aurélio

    2013-01-01

    The protozoan parasite Trypanosoma cruzi displays similarities to fungi in terms of its sterol lipid biosynthesis, as ergosterol and other 24-alkylated sterols are its principal endogenous sterols. The sterol pathway is thus a potential drug target for the treatment of Chagas disease. We describe here a comparative study of the growth inhibition, ultrastructural and physiological changes leading to the death of T. cruzi cells following treatment with the sterol biosynthesis inhibitors (SBIs) ketoconazole and lovastatin. We first calculated the drug concentration inhibiting epimastigote growth by 50% (EC50/72 h) or killing all cells within 24 hours (EC100/24 h). Incubation with inhibitors at the EC50/72 h resulted in interesting morphological changes: intense proliferation of the inner mitochondrial membrane, which was corroborated by flow cytometry and confocal microscopy of the parasites stained with rhodamine 123, and strong swelling of the reservosomes, which was confirmed by acridine orange staining. These changes to the mitochondria and reservosomes may reflect the involvement of these organelles in ergosterol biosynthesis or the progressive autophagic process culminating in cell lysis after 6 to 7 days of treatment with SBIs at the EC50/72 h. By contrast, treatment with SBIs at the EC100/24 h resulted in rapid cell death with a necrotic phenotype: time-dependent cytosolic calcium overload, mitochondrial depolarization and reservosome membrane permeabilization (RMP), culminating in cell lysis after a few hours of drug exposure. We provide the first demonstration that RMP constitutes the “point of no return” in the cell death cascade, and propose a model for the necrotic cell death of T. cruzi. Thus, SBIs trigger cell death by different mechanisms, depending on the dose used, in T. cruzi. These findings shed new light on ergosterol biosynthesis and the mechanisms of programmed cell death in this ancient protozoan parasite. PMID:23383204

  8. Sterol Modulation of the Plasma Membrane H+-ATPase Activity from Corn Roots Reconstituted into Soybean Lipids.

    PubMed Central

    Grandmougin-Ferjani, A.; Schuler-Muller, I.; Hartmann, M. A.

    1997-01-01

    A partially purified H+-ATPase from the plasma membrane (PM) of corn (Zea mays L.) roots was inserted into vesicles prepared with soybean (Glycine max L.) phospholipids and various concentrations of individual sterols using either a freeze-thaw sonication or an octylglucoside dilution procedure. Both methods yielded a functional enzyme that retained its native characteristics. We have investigated the effects of typical plant sterols (i.e. sitosterol, stigmasterol, and 24-methylcholesterol) on both ATP hydrolysis and H+ pumping by the reconstituted corn root PM ATPase. We have also checked the influence of cholesterol and of two unusual sterols, 24-methylpollinastanol and 14[alpha],24-dimethylcholest-8-en-3[beta]-ol. Here we present evidence for a sterol modulation of the plant PM H+-ATPase activity. In particular, cholesterol and stigmasterol were found to stimulate the pump, especially when present at 5 mol%, whereas all of the other sterols tested behaved as inhibitors at any concentration in proteoliposomes. In all situations H+ pumping was shown to be more sensitive to a sterol environment than was ATP hydrolysis. Our results suggest the occurrence of binding sites for sterols on the plant PM H+-ATPase. PMID:12223599

  9. Sterol-dependent nuclear import of ORP1S promotes LXR regulated trans-activation of apoE

    SciTech Connect

    Lee, Sungsoo; Wang, Ping-Yuan; Jeong, Yangsik; Mangelsdorf, David J.; Anderson, Richard G.W.; Michaely, Peter

    2012-10-01

    Oxysterol binding protein related protein 1S (ORP1S) is a member of a family of sterol transport proteins. Here we present evidence that ORP1S translocates from the cytoplasm to the nucleus in response to sterol binding. The sterols that best promote nuclear import of ORP1S also activate the liver X receptor (LXR) transcription factors and we show that ORP1S binds to LXRs, promotes binding of LXRs to LXR response elements (LXREs) and specifically enhances LXR-dependent transcription via the ME.1 and ME.2 enhancer elements of the apoE gene. We propose that ORP1S is a cytoplasmic sterol sensor, which transports sterols to the nucleus and promotes LXR-dependent gene transcription through select enhancer elements. -- Highlights: Black-Right-Pointing-Pointer ORP1S translocates to the nucleus in response to sterol binding. Black-Right-Pointing-Pointer The sterols that best promote nuclear import of ORP1S are LXR agonists. Black-Right-Pointing-Pointer ORP1S binds to LXRs, enhances binding of LXRs to LXREs and promotes LXR-dependent transcription of apoE.

  10. The synthesis map is a multidimensional educational tool that provides insight into students' mental models and promotes students' synthetic knowledge generation.

    PubMed

    Ortega, Ryan A; Brame, Cynthia J

    2015-01-01

    Concept mapping was developed as a method of displaying and organizing hierarchical knowledge structures. Using the new, multidimensional presentation software Prezi, we have developed a new teaching technique designed to engage higher-level skills in the cognitive domain. This tool, synthesis mapping, is a natural evolution of concept mapping, which utilizes embedding to layer information within concepts. Prezi's zooming user interface lets the author of the presentation use both depth as well as distance to show connections between data, ideas, and concepts. Students in the class Biology of Cancer created synthesis maps to illustrate their knowledge of tumorigenesis. Students used multiple organizational schemes to build their maps. We present an analysis of student work, placing special emphasis on organization within student maps and how the organization of knowledge structures in student maps can reveal strengths and weaknesses in student understanding or instruction. We also provide a discussion of best practices for instructors who would like to implement synthesis mapping in their classrooms.

  11. The Origin of Sterol Biosynthesis: A Time-Point for the Evolution of Eukaryotes and the Presence of O2

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Budin, M.; Brocks, J. J.

    2003-12-01

    The evolution of sterol biosynthesis is of critical interest to geoscientists as well as to evolutionary biologists. The first enzyme in the pathway, squalene monooxygenase (Sqmo), requires molecular oxygen (O2), suggesting that this process post-dates the evolution of Cyanobacteria. Additionally, the presence of steranes in ancient rocks marks the suggested time-point of eukaryogenesis(1). Sterol biosynthesis is viewed primarily as a eukaryotic process, and the frequency of its occurrence in bacteria long has been a subject of controversy. In this work, 19 protein gene sequences for Sqmo from eukaryotes were compared to all available complete and partial prokaryotic genomes. Twelve protein gene sequences representing oxidosqualene cyclase (Osc), the second enzyme of the sterol biosynthetic pathway, also were examined. The only unequivocal matches among the bacteria were the alpha-proteobacterium, Methylococcus capsulatus, in which sterol biosynthesis already is known, and the planctomycete, Gemmata obscuriglobus. The latter species contains the most abbreviated sterol pathway yet identified in any organism. Experiments show that the major sterols in Gemmata are lanosterol and its uncommon isomer, parkeol. In bacteria, the sterol biosynthesis genes occupy a contiguous coding region and may represent a single operon. Phylogenetic trees show that the sterol pathway in bacteria and eukaryotes has a common ancestry. Gemmata may retain the most ancient remnants of the pathway's origin, and it is likely that sterol biosynthesis in eukaryotes was acquired through gene transfer from bacteria. However, this work indicates that no known prokaryotes could produce the 24-ethyl steranes found in Archaean rocks(1). Therefore these compounds remain indicative of the presence of both eukaryotes and O2 at 2.7 Ga. 1. J. J. Brocks, G. A. Logan, R. Buick, R. E. Summons, (1999) Science 285, 1033-1036.

  12. The Synthesis Map Is a Multidimensional Educational Tool That Provides Insight into Students' Mental Models and Promotes Students' Synthetic Knowledge Generation

    ERIC Educational Resources Information Center

    Ortega, Ryan A.; Brame, Cynthia J.

    2015-01-01

    Concept mapping was developed as a method of displaying and organizing hierarchical knowledge structures. Using the new, multidimensional presentation software Prezi, we have developed a new teaching technique designed to engage higher-level skills in the cognitive domain. This tool, synthesis mapping, is a natural evolution of concept mapping,…

  13. Sterol carrier protein-2 alters high density lipoprotein-mediated cholesterol efflux.

    PubMed

    Atshaves, B P; Starodub, O; McIntosh, A; Petrescu, A; Roths, J B; Kier, A B; Schroeder, F

    2000-11-24

    Although sterol carrier protein-2 (SCP-2) participates in the uptake and intracellular trafficking of cholesterol, its effect on "reverse cholesterol transport" has not been explored. As shown herein, SCP-2 expression inhibited high density lipoprotein (HDL)-mediated efflux of [(3)H]cholesterol and fluorescent 22-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3b-ol (NBD-cholesterol) up to 61 and 157%, respectively. Confocal microscopy of living cells allowed kinetic analysis of two intracellular pools of HDL-mediated NBD-cholesterol efflux: the highly fluorescent lipid droplet pool and the less fluorescent pool outside the lipid droplets, designated the cytoplasmic compartment. Both the whole cell and the cytoplasmic compartment exhibited two similar kinetic pools, the half-times of which were consistent with protein (t(b)(12) near 1 min) and vesicular (t(d)(12) = 10-20 min) mediated sterol transfer. Although SCP-2 expression did not alter cytoplasmic sterol pool sizes, the rapid t(b)(12) decreased 36%, while the slower t(d)(12) increased 113%. Lipid droplets also exhibited two kinetic pools of NBD-cholesterol efflux but with half-times over 200% shorter than those of the cytoplasmic compartment. The lipid droplet slower effluxing pool size and t(d)(12) were increased 48% and 115%, respectively, in SCP-2-expressing cells. Concomitantly, the level of the lipid droplet-specific adipose differentiation-related protein decreased 70%. Overall, HDL-mediated sterol efflux from L-cell fibroblasts reflected that of the cytoplasmic rather than lipid droplet compartment. SCP-2 differentially modulated sterol efflux from the two cytoplasmic pools. However, net efflux was determined primarily by inhibition of the slowly effluxing pool rather than by acceleration of the rapid protein-mediated pool. Finally, SCP-2 expression also inhibited sterol efflux from lipid droplets, an effect related to decreased adipose differentiation-related protein, a lipid

  14. The effects of growth temperature on the methyl sterol and phospholipid fatty acid composition of Methylococcus capsulatus (Bath)

    NASA Technical Reports Server (NTRS)

    Jahnke, L. L.

    1992-01-01

    Growth of Methylococcus capsulatus (Bath) at temperatures ranging from 30 to 50 degrees C resulted in changes to the whole cell lipid constituents. As temperature was lowered, the overall proportion of hexadecenoic acid (C16:1) increased, and the relative proportions of the delta 9, delta 10 and delta 11 C16:1 double bond positional isomers changed. Methyl sterol content also increased as the growth temperature was lowered. The highest amounts of methyl sterol were found in 30 degrees C cells and the lowest in 50 degrees C cells (sterol-phospholipid ratios of 0.077 and 0.013, respectively). The data are consistent with a membrane modulating role for the sterol produced by this prokaryotic organism.

  15. The effects of growth temperature on the methyl sterol and phospholipid fatty acid composition of Methylococcus capsulatus (Bath)

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda L.

    1992-01-01

    Growth of Methylococcus capsulatus (Bath) at temperatures ranging from 30 to 50 C resulted in changes to the whole cell lipid constituents. As temperature was lowered, the overall proportion of hexadecenoic acid (C16:1) increased, and the relative proportions of the Delta9, Delta10, and Delta11 C16:1 double bond positional isomers changed. Methyl sterol content also increased as the growth temperature was lowered. The highest amounts of methyl sterol were found in 30 C cells and the lowest in 50 C cells (sterol-phospholipid ratios of 0.077 and 0.013, respectively). The data are consistent with a membrane modulating role for the sterol produced by this prokaryotic organism.

  16. Structural Features and Potent Antidepressant Effects of Total Sterols and β-sitosterol Extracted from Sargassum horneri

    PubMed Central

    Zhao, Donghai; Zheng, Lianwen; Qi, Ling; Wang, Shuran; Guan, Liping; Xia, Yanan; Cai, Jianhui

    2016-01-01

    The purified total sterols and β-sitosterol extracted from Sargassum horneri were evaluated for their antidepressant-like activity using the forced swim test (FST) and tail suspension test (TST) in mice. Total sterols and β-sitosterol significantly reduced the immobility time in the FST and TST. Total sterols were administered orally for 7 days at doses of 50, 100, and 200 mg/kg, and β-sitosterol was administered intraperitoneally at doses of 10, 20, and 30 mg/kg. β-sitosterol had no effect on locomotor activity in the open field test. In addition, total sterols and β-sitosterol significantly increased NE, 5-HT, and the metabolite 5-HIAA in the mouse brain, suggesting that the antidepressant-like activity may be mediated through these neurotransmitters. PMID:27367705

  17. The Synthesis Map Is a Multidimensional Educational Tool That Provides Insight into Students’ Mental Models and Promotes Students’ Synthetic Knowledge Generation

    PubMed Central

    Ortega, Ryan A.; Brame, Cynthia J.

    2015-01-01

    Concept mapping was developed as a method of displaying and organizing hierarchical knowledge structures. Using the new, multidimensional presentation software Prezi, we have developed a new teaching technique designed to engage higher-level skills in the cognitive domain. This tool, synthesis mapping, is a natural evolution of concept mapping, which utilizes embedding to layer information within concepts. Prezi’s zooming user interface lets the author of the presentation use both depth as well as distance to show connections between data, ideas, and concepts. Students in the class Biology of Cancer created synthesis maps to illustrate their knowledge of tumorigenesis. Students used multiple organizational schemes to build their maps. We present an analysis of student work, placing special emphasis on organization within student maps and how the organization of knowledge structures in student maps can reveal strengths and weaknesses in student understanding or instruction. We also provide a discussion of best practices for instructors who would like to implement synthesis mapping in their classrooms. PMID:25917385

  18. A Sterol and Spiroditerpenoids from a Penicillium sp. Isolated from a Deep Sea Sediment Sample

    PubMed Central

    Li, Yan; Ye, Dezan; Shao, Zongze; Cui, Chengbin; Che, Yongsheng

    2012-01-01

    A new polyoxygenated sterol, sterolic acid (1), three new breviane spiroditerpenoids, breviones I–K (2–4), and the known breviones (5–8), were isolated from the crude extract of a Penicillium sp. obtained from a deep sea sediment sample that was collected at a depth of 5115 m. The structures of 1–4 were elucidated primarily by NMR experiments, and 1 was further confirmed by X-ray crystallography. The absolute configurations of 2 and 3 were deduced by comparison of their CD spectra with those of the model compounds. Compounds 2 and 5 showed significant cytotoxicity against MCF-7 cells, which is comparable to the positive control cisplatin. PMID:22412815

  19. [Terpenoids and sterols from Ricinus communis and their activities against diabetes].

    PubMed

    Li, Shen-Hua; Deng, Qing; Zhu, Li; Lai, Chun-Hua; Wang, Heng-Shan; Tan, Qin-Gang

    2014-02-01

    Seven terpenoids and three sterols were isolated from the methanol extracts of the aerial parts of Ricinus communis by chromatography methods and their structures were identified by spectra analysis as ficusic acid( 1), phytol(2), callyspinol(3) , lupeol(4), 30-norlupan-3beta-ol-20-one(5) , lup-20(29)-en-3beta,15alpha-diol(6) , acetylaleuritolic acid( 7), stigmast4-en-3-one(8) , stig-mast-4-en-6beta-ol-3-one(9) , and stigmast4-en-3,6-dione(10). Compounds 1-3 and 5-10 were obtained from this species for the first time and 5 and 6 showed significant inhibitive activity and good selectivity against 11beta-HSD of mouse and human in vitro. [Key words] Ricinus communis; terpenoids; sterols; 11beta-HSD

  20. Microbial water quality and sedimentary faecal sterols as markers of sewage contamination in Kuwait.

    PubMed

    Lyons, B P; Devlin, M J; Abdul Hamid, S A; Al-Otiabi, A F; Al-Enezi, M; Massoud, M S; Al-Zaidan, A S; Smith, A J; Morris, S; Bersuder, P; Barber, J L; Papachlimitzou, A; Al-Sarawi, H A

    2015-11-30

    Microbial water quality and concentrations of faecal sterols in sediment have been used to assess the degree of sewage contamination in Kuwait's marine environment. A review of microbial (faecal coliform, faecal streptococci and Escherichia coli) water quality data identified temporal and spatial sources of pollution around the coastline. Results indicated that bacterial counts regularly breach regional water quality guidelines. Sediments collected from a total of 29 sites contained detectable levels of coprostanol with values ranging from 29 to 2420 ng g(-1) (dry weight). Hot spots based on faecal sterol sediment contamination were identified in Doha Bay and Sulaibikhat Bay, which are both smaller embayments of Kuwait Bay. The ratio of epicoprostanol/coprostanol indicates that a proportion of the contamination was from raw or partially treated sewage. Sewage pollution in these areas are thought to result from illegal connections and discharges from storm drains, such as that sited at Al-Ghazali.

  1. Antioxidative succinobucol-sterol conjugates: Crystal structures and pseudosymmetry in the crystals

    NASA Astrophysics Data System (ADS)

    Ikonen, Satu; Jurček, Ondřej; Wimmer, Zdeněk; Drašar, Pavel; Kolehmainen, Erkki

    2012-03-01

    An extensive study to attach succinobucol to sterols has provided conjugates which comprise two pharmaceutically important compounds into one entity where the components are expected to have a synergistic effect. The motivation to design these novel conjugates was the need to broaden the armamentarium of current agents used in the treatment of atherosclerotic diseases and type 2 diabetes. In desire for detailed information of these compounds in solid state, which also have an influence to their physiological activity, systematic crystallization experiments were performed and as a result, X-ray quality single crystals were obtained from four succinobucol-sterol conjugates. All of these compounds crystallized in space group P1 with two or four molecules in an asymmetric unit and the crystallographically independent molecules were found to be related by pseudosymmetry (i.e. by pseudoinversion in 1-3 and by pseudoinversion plus pseudotranslation in 4).

  2. Sterol Biosynthesis in Sub-Cellular Particles of Higher Plants 1

    PubMed Central

    Knapp, F. F.; Aexel, R. T.; Nicholas, H. J.

    1969-01-01

    Mevalonic acid-2-14C was administered to cut stems of bean seedlings (Phaseolus vulgaris L.) for time intervals varying from 20 min to 24 hr. The plants were homogenized in a pH 7.8 tris-sucrose buffer and the homogenates separated into chloroplast, mitochondrial, microsomal, and supernatant fractions by means of differential centrifugation. The distribution of radioactivity into non-saponifiable material in each of the fractions was then determined. After short incubation periods labeled squalene was localized in the supernatant fraction. Labeled sterol was limited at all incubation periods to the microsomal and supernatant fractions. The data presented clearly implicate the microsomal and supernatant fractions in sterol biosynthesis in higher plants. PMID:16657081

  3. Dysregulation of sterol response element-binding proteins and downstream effectors in prostate cancer during progression to androgen independence.

    PubMed

    Ettinger, Susan L; Sobel, Richard; Whitmore, Tanis G; Akbari, Majid; Bradley, Dawn R; Gleave, Martin E; Nelson, Colleen C

    2004-03-15

    Androgen ablation, the most common therapeutic treatment used for advanced prostate cancer, triggers the apoptotic regression of prostate tumors. However, remissions are temporary because surviving prostate cancer cells adapt to the androgen-deprived environment and form androgen-independent (AI) tumors. We hypothesize that adaptive responses of surviving tumor cells result from dysregulated gene expression of key cell survival pathways. Therefore, we examined temporal alterations to gene expression profiles in prostate cancer during progression to androgen independence at several time points using the LNCaP xenograft tumor model. Two key genes, sterol response element-binding protein (SREBP)-1 and -2 (SREBP-1a,-1c, and -2), were consistently dysregulated. These genes are known to coordinately control the expression of the groups of enzymes responsible for lipid and cholesterol synthesis. Northern blots revealed modest increased expression of SREBP-1a, -1c, and -2 after castration, and at androgen independence (day 21-28), the expression levels of both SREBP-1a and -1c were significantly greater than precastrate levels. Changes in SREBP-1 and -2 protein expression were observed by Western analysis. SREBP-1 68-kDa protein levels were maintained throughout progression, however, SREBP-2 68-kDa protein expression increased after castration and during progression (3-fold). SREBPs are transcriptional regulators of over 20 functionally related enzymes that coordinately control the metabolic pathways of lipogenesis and cholesterol synthesis, some of which were likewise dysregulated during progression to androgen independence. RNA levels of acyl-CoA-binding protein/diazepam-binding inhibitor and fatty acid synthase decreased significantly after castration, and then, during progression, increased to levels greater than or equal to precastrate levels. Expression of farnesyl diphosphate synthase did not decrease after castration but did increase significantly during

  4. Potential of the Desert Locust Schistocerca gregaria (Orthoptera: Acrididae) as an Unconventional Source of Dietary and Therapeutic Sterols.

    PubMed

    Cheseto, Xavier; Kuate, Serge Philibert; Tchouassi, David P; Ndung'u, Mary; Teal, Peter E A; Torto, Baldwyn

    2015-01-01

    Insects are increasingly being recognized not only as a source of food to feed the ever growing world population but also as potential sources of new products and therapeutic agents, among which are sterols. In this study, we sought to profile sterols and their derivatives present in the desert locust, Schistocerca gregaria, focusing on those with potential importance as dietary and therapeutic components for humans. Using coupled gas chromatography-mass spectrometry (GC-MS), we analyzed and compared the quantities of sterols in the different sections of the gut and tissues of the locust. In the gut, we identified 34 sterols which showed a patchy distribution, but with the highest composition in the foregut (55%) followed by midgut (31%) and hindgut (14%). Fed ad libitum on wheat seedlings, five sterols unique to the insect were detected. These sterols were identified as 7-dehydrocholesterol, desmosterol, fucosterol, (3β, 5α) cholesta-8, 14, 24-trien-3-ol, 4, 4-dimethyl, and (3β, 20R) cholesta-5, 24-dien-3, 20-diol with the first three having known health benefits in humans. Incubation of the fore-, mid- and hindgut with cholesterol-[4-13C] yielded eight derivatives, three of these were detected in the gut of the desert locust after it had consumed the vegetative diet but were not detected in the diet. Our study shows that the desert locust ingests phytosterols from a vegetative diet and, amplifies and metabolizes them into derivatives with potential salutary benefits and we discuss our findings in this context.

  5. Structural Sterols Are Involved in Both the Initiation and Tip Growth of Root Hairs in Arabidopsis thaliana[W

    PubMed Central

    Ovečka, Miroslav; Berson, Tobias; Beck, Martina; Derksen, Jan; Šamaj, Jozef; Baluška, František; Lichtscheidl, Irene K.

    2010-01-01

    Structural sterols are abundant in the plasma membrane of root apex cells in Arabidopsis thaliana. They specifically accumulate in trichoblasts during the prebulging and bulge stages and show a polar accumulation in the tip during root hair elongation but are distributed evenly in mature root hairs. Thus, structural sterols may serve as a marker for root hair initiation and growth. In addition, they may predict branching events in mutants with branching root hairs. Structural sterols were detected using the sterol complexing fluorochrome filipin. Application of filipin caused a rapid, concentration-dependent decrease in tip growth. Filipin-complexed sterols accumulated in globular structures that fused to larger FM4-64–positive aggregates in the tip, so-called filipin-induced apical compartments, which were closely associated with the plasma membrane. The plasma membrane appeared malformed and the cytoarchitecture of the tip zone was affected. Trans-Golgi network/early endosomal compartments containing molecular markers, such as small Rab GTPase RabA1d and SNARE Wave line 13 (VTI12), locally accumulated in these filipin-induced apical compartments, while late endosomes, endoplasmic reticulum, mitochondria, plastids, and cytosol were excluded from them. These data suggest that the local distribution and apical accumulation of structural sterols may regulate vesicular trafficking and plasma membrane properties during both initiation and tip growth of root hairs in Arabidopsis. PMID:20841426

  6. High lipid order of Arabidopsis cell-plate membranes mediated by sterol and DYNAMIN-RELATED PROTEIN1A function.

    PubMed

    Frescatada-Rosa, Márcia; Stanislas, Thomas; Backues, Steven K; Reichardt, Ilka; Men, Shuzhen; Boutté, Yohann; Jürgens, Gerd; Moritz, Thomas; Bednarek, Sebastian Y; Grebe, Markus

    2014-12-01

    Membranes of eukaryotic cells contain high lipid-order sterol-rich domains that are thought to mediate temporal and spatial organization of cellular processes. Sterols are crucial for execution of cytokinesis, the last stage of cell division, in diverse eukaryotes. The cell plate of higher-plant cells is the membrane structure that separates daughter cells during somatic cytokinesis. Cell-plate formation in Arabidopsis relies on sterol- and DYNAMIN-RELATED PROTEIN1A (DRP1A)-dependent endocytosis. However, functional relationships between lipid membrane order or lipid packing and endocytic machinery components during eukaryotic cytokinesis have not been elucidated. Using ratiometric live imaging of lipid order-sensitive fluorescent probes, we show that the cell plate of Arabidopsis thaliana represents a dynamic, high lipid-order membrane domain. The cell-plate lipid order was found to be sensitive to pharmacological and genetic alterations of sterol composition. Sterols co-localize with DRP1A at the cell plate, and DRP1A accumulates in detergent-resistant membrane fractions. Modifications of sterol concentration or composition reduce cell-plate membrane order and affect DRP1A localization. Strikingly, DRP1A function itself is essential for high lipid order at the cell plate. Our findings provide evidence that the cell plate represents a high lipid-order domain, and pave the way to explore potential feedback between lipid order and function of dynamin-related proteins during cytokinesis.

  7. [Basic mechanisms: absorption and excretion of cholesterol and other sterols].

    PubMed

    Cofan Pujol, Montserrat

    2014-01-01

    Cholesterol is of vital importance for vertebrate cell membrane structure and function. It is obvious that adequate regulation of cholesterol homeostasis is essential. Hypercholesterolemia promotes atherosclerosis and thereby represents a major risk factor for cardiovascular disease. The liver has been considered the major site of control in maintenance of cholesterol homeostasis. The liver facilitates clearance of (very) low density lipoprotein particles and cholesterol-containing chylomicron remnants, synthesizes cholesterol, synthesizes and secretes (nascent) high density lipoprotein particles, secretes cholesterol and bile salts to bile, and is involved in reverse cholesterol transport. In recent years, however, the importance of the intestine in many aspects of cholesterol physiology is increasingly recognized. It has become apparent that direct secretion of cholesterol from the blood compartment into the intestine, or transintestinal cholesterol excretion, plays a major role in disposal of cholesterol via the feces. This review will discuss current knowledge on the physiology of cholesterol homeostasis, with emphasis on cholesterol absorption, cholesterol synthesis and fecal excretion, and therapeutic options for hypercholesterolemia.

  8. Defective peroxisomal catabolism of branched fatty acyl coenzyme A in mice lacking the sterol carrier protein-2/sterol carrier protein-x gene function

    PubMed Central

    Seedorf, Udo; Raabe, Martin; Ellinghaus, Peter; Kannenberg, Frank; Fobker, Manfred; Engel, Thomas; Denis, Simone; Wouters, Fred; Wirtz, Karel W.A.; Wanders, Ronald J.A.; Maeda, Nobuyo; Assmann, Gerd

    1998-01-01

    Gene targeting in mice was used to investigate the unknown function of Scp2, encoding sterol carrier protein-2 (SCP2; a peroxisomal lipid carrier) and sterol carrier protein-x (SCPx; a fusion protein between SCP2 and a peroxisomal thiolase). Complete deficiency of SCP2 and SCPx was associated with marked alterations in gene expression, peroxisome proliferation, hypolipidemia, impaired body weight control, and neuropathy. Along with these abnormalities, catabolism of methyl-branched fatty acyl CoAs was impaired. The defect became evident from up to 10-fold accumulation of the tetramethyl-branched fatty acid phytanic acid in Scp2(−/−) mice. Further characterization supported that the gene disruption led to inefficient import of phytanoyl-CoA into peroxisomes and to defective thiolytic cleavage of 3-ketopristanoyl-CoA. These results corresponded to high-affinity binding of phytanoyl-CoA to the recombinant rat SCP2 protein, as well as high 3-ketopristanoyl-CoA thiolase activity of the recombinant rat SCPx protein. PMID:9553048

  9. Sterol glycosyltransferases required for adaptation of Withania somnifera at high temperature.

    PubMed

    Singh, Gaurav; Tiwari, Manish; Singh, Surendra Pratap; Singh, Ruchi; Singh, Surendra; Shirke, Pramod Arvind; Trivedi, Prabodh K; Misra, Pratibha

    2017-03-16

    Heat is a major environmental stress factor that confines growth, productivity, and metabolism of plants. Plants respond to such unfavorable conditions through changes in their physiological, biochemical and developmental processes. Withania somnifera, an important medicinal plant, grows in hot and dry conditions, however, molecular mechanisms related to such adaptive properties are not known. Here, we elucidated that members of the SGT gene family play important roles in the survival of W. somnifera under adverse conditions through maintaining the integrity of the membrane. SGTs are enzymes involved in sterol modifications and participate in metabolic flexibility during stress. Silencing of WsSGT members, for instance WsSGTL1, WsSGTL2 and WsSGTL4, was inimical for important physiological parameters, such as electron transport rate, photochemical quantum yield, acceptor side limitation, non-photochemical quenching, Fv/Fm and net photosynthetic rate, whereas stomatal conductance, transpiration rate and dark respiration rates were increased. Decreased non-photochemical quenching and increased respiration rates helped to generate significant amount of ROS in the Wsamisgt lines. After heat stress, H2 O2 , lipid peroxidation and nitric oxide production increased in the Wsamisgt lines due to high ROS generation. The expression of HSPs in Wsamisgt lines might be involved in regulation of physiological processes during stress. We have also observed increased proline accumulation which might be involved in restricting water loss in the Wsamisgt lines. Taken together, our observations revealed that SGTL enzyme activity is required to maintain the internal damages of the cell against high temperature by maintaining the sterol versus sterol glycosides ratio in the membranes of W. somnifera. Abbreviations - amiRNA, artificial miRNA; E, transpiration rate; gs, stomatal conductance; NO, nitric oxide; Pn, photosynthetic rate; Rd, respiration rate; ROS, reactive oxygen species; SGT

  10. Sources of plant sterol contaminants encountered in low level steroid analysis.

    PubMed

    Banner, C D

    1991-12-06

    During development of an analytical method to characterize ligands to new members of the steroid hormone receptor superfamily, a persistant contaminant profile was observed during gas chromatographic analysis of reagent blanks. Mass spectrometric analysis identified three of the contaminant peaks as cholesterol and the plant sterols stigmasterol and sitosterol. Laboratory articles made of natural rubber, i.e. pipette fillers and latex gloves, were found to be the source of these and other compounds in the reagent blank profile.

  11. An efficient diethyl ether-based soxhlet protocol to quantify faecal sterols from catchment waters.

    PubMed

    Shah, Vikas Kumar G; Dunstan, Hugh; Taylor, Warren

    2006-03-03

    A study was conducted to evaluate the efficiency and reproducibility of a diethyl ether-based soxhlet extraction procedure for faecal sterols occurring from catchment waters. Water samples spiked with a mixture of faecal sterols were filtered and analytes were extracted using the diethyl ether-based soxhlet method and the Bligh and Dyer chloroform extraction process. For diethyl ether-based soxhlet extraction procedure, solvent extracts were saponified with 100 microL of 10% KOH in methanol (100 degrees C/120 min) and then acidified with 60 microL of 6M HCl. Lipid contents were extracted by ethanol (0.5 mL) from the saponification products. The lipid extracts were then reacted with 100 microL of bis(trimethyl)trifluoroacetamide (BSTFA) containing 1% trimethyl chlorosilane (100 degrees C/60 min) to form the trimethylsilyl (TMS) derivatives. The derivatised extracts were then analyzed by gas chromatography-mass spectrometry. For sterol concentrations ranging from 35 to 175 microg mL(-1), the soxhlet-based extraction process yielded the following recovery efficiencies for coprostanol (101%), epicoprostanol (97%), cholesterol (97%), dihydrocholesterol (97%) and 5alpha-cholestane (111%), whereas the Bligh and Dyer process yielded recoveries of 32, 41, 0, 36 and 51%, respectively. The results suggested that the diethyl ether-based soxhlet extraction method was more efficient and reproducible than the Bligh and Dyer chloroform extraction process for the analyses of trace levels of faecal sterols from water samples. Moreover, it was revealed that the diethyl ether-based soxhlet extraction method used less solvent and was logistically easier.

  12. Key scientific findings and policy- and health-relevant insights from the U.S. Environmental Protection Agency's Particulate Matter Supersites Program and related studies: an integration and synthesis of results.

    PubMed

    Solomon, Paul A; Hopke, Philip K; Froines, John; Scheffe, Richard

    2008-01-01

    In 1998, the U.S. Environmental Protection Agency (EPA) initiated a major air quality program known as the Particulate Matter (PM) Supersites Program. The Supersites Program was a multiyear, $27 million air quality monitoring program consisting of eight regional air quality projects located throughout the United States, each with differing atmospheric pollution conditions resulting from variations in source emissions and meteorology. The overall goal of the program was to elucidate source-receptor relationships and atmospheric processes leading to PM accumulation on urban and regional scales; thus providing the scientific underpinning for modeling and data analysis efforts to support State Implementation Plans and more effective risk management approaches for PM. The program had three main objectives: (1) conduct methods development and evaluation, (2) characterize ambient PM, and (3) support health effects and exposure research. This paper provides a synthesis of key scientific findings from the Supersites Program and related studies. EPA developed 16 science/policy-relevant questions in conjunction with state and other federal agencies, Regional Planning Organizations, and the private sector. These questions were addressed to the extent possible, even given the vast amount of new information available from the Supersites Program, in a series of papers published as a special issue of the Journal of Air & Waste Management Association (February 2008). This synthesis also includes discussions of: (1) initial Supersites Program support for air quality management efforts in specific locations throughout the United States; (2) selected policy-relevant insights, based on atmospheric sciences findings, useful to air quality managers and decision makers planning emissions management strategies to address current and future PM National Ambient Air Quality Standards (NAAQS) and network planning and implementation; (3) selected health-relevant insights interpreted from

  13. Structure and Biological Evaluation of Novel Cytotoxic Sterol Glycosides from the Marine Red Alga Peyssonnelia sp.

    PubMed Central

    Lin, An-Shen; Engel, Sebastian; Smith, Benjamin A.; Fairchild, Craig R.; Aalbersberg, William; Hay, Mark E.; Kubanek, Julia

    2010-01-01

    Bioactivity-guided fractionation of the extract from a Fijian red alga Peyssonnelia sp. led to the isolation of two novel sterol glycosides 19-O-β-d-glucopyranosyl-19-hydroxy-cholest-4-en-3-one (1) and 19-O-β-d-N-acetyl-2-aminoglucopyranosyl-19-hydroxy-cholest-4-en-3-one (2), and two known alkaloids indole-3-carboxaldehyde (3) and 3-(hydroxyacetyl)indole (4). Their structures were characterized by 1D and 2D NMR and mass spectral analysis. The sterol glycosides inhibited cancer cell growth with mean IC50 values (for 11 human cancer cell lines) of 1.63 and 1.41 µM for 1 and 2, respectively. The most sensitive cancer cell lines were MDA-MB-468 (breast) and A549 (lung), with IC50s in of 0.71–0.97 µM for 1 and 2. Modification of the sterol glycoside structures revealed that the α,β-unsaturated ketone at C-3 and oxygenation at C-19 of 1 and 2 are crucial for anticancer activity, whereas the glucosidic group was not essential but contributed to enhanced activity against the most sensitive cell lines. PMID:21036050

  14. Fatty acids, sterols, and antioxidant activity in minimally processed avocados during refrigerated storage.

    PubMed

    Plaza, Lucía; Sánchez-Moreno, Concepción; de Pascual-Teresa, Sonia; de Ancos, Begoña; Cano, M Pilar

    2009-04-22

    Avocado ( Persea americana Mill.) is a good source of bioactive compounds such as monounsaturated fatty acids and sterols. The impact of minimal processing on its health-promoting attributes was investigated. Avocados cut into slices or halves were packaged in plastic bags under nitrogen, air, or vacuum and stored at 8 degrees C for 13 days. The stabilities of fatty acids and sterols as well as the effect on antioxidant activity were evaluated. The main fatty acid identified and quantified in avocado was oleic acid (about 57% of total content), whereas beta-sitosterol was found to be the major sterol (about 89% of total content). In general, after refrigerated storage, a significant decrease in fatty acid content was observed. Vacuum/halves and air/slices were the samples that maintained better this content. With regard to phytosterols, there were no significant changes during storage. Antioxidant activity showed a slight positive correlation against stearic acid content. At the end of refrigerated storage, a significant increase in antiradical efficiency (AE) was found for vacuum samples. AE values were quite similar among treatments. Hence, minimal processing can be a useful tool to preserve health-related properties of avocado fruit.

  15. Sterol 14alpha-Demethylase (CYP51) as a Therapeutic Target for Human Trypanosomiasis and Leishmaniasis

    PubMed Central

    Lepesheva, Galina I.; Waterman, Michael R.

    2012-01-01

    Pathogenic protozoa threaten lives of several hundred million people throughout the world and are responsible for large numbers of deaths globally. The parasites are transmitted to humans by insect vectors, more than a hundred of infected mammalian species forming reservoir. With human migrations, HIV-coinfections, and blood bank contamination the diseases are now spreading beyond the endemic tropical countries, being found in all parts of the world including the USA, Canada and Europe. In spite of the widely appreciated magnitude of this health problem, current treatment for sleeping sickness (Trypanosoma brucei), Chagas disease (Trypanosoma cruzi) and leishmaniasis (Leishmania spp.) remains unsatisfactory. The drugs are decades old, their efficacy and safety profiles are unacceptable. This review describes sterol 14α-demethylase, an essential enzyme in sterol biosynthesis in eukaryotes and clinical target for antifungal azoles, as a promising target for antiprotozoan chemotherapy. While several antifungal azoles have been proven active against Trypanosomatidae and are under consideration as antiprotozoan agents, crystal structures of sterol 14α-demethylases from three protozoan pathogens, Trypanosoma brucei, Trypanosoma cruzi and Leishmania infantum provide the basis for the development of new, highly potent and pathogen-specific drugs with rationally optimized pharmacological properties. PMID:21619513

  16. [Microbial metabolites that inhibit sterol biosynthesis, their chemical diversity and characteristics of mode of action].

    PubMed

    Trenin, A S

    2013-01-01

    Inhibitors of sterol biosynthesis (ISB) are widespread in nature and characterized by appreciable diversity both in their chemical structure and mode of action. Many of these inhibitors express noticeable biological activity and approved themselves in development of various pharmaceuticals. In this review there is a detailed description of biologically active microbial metabolites with revealed chemical structure that have ability to inhibit sterol biosynthesis. Inhibitors of mevalonate pathway in fungous and mammalian cells, exhibiting hypolipidemic or antifungal activity, as well as inhibitors of alternative non-mevalonate (pyruvate gliceraldehyde phosphate) isoprenoid pathway, which are promising in the development of affective antimicrobial or antiparasitic drugs, are under consideration in this review. Chemical formulas of the main natural inhibitors and their semi-synthetic derivatives are represented. Mechanism of their action at cellular and biochemical level is discussed. Special attention is given to inhibitors of 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase (group of lovastatin) and inhibitors of acyl-CoA-cholesterol-acyl transferase (ACAT) that possess hypolipidemic activity and could be affective in the treatment of atherosclerosis. In case of inhibitors of late stages of sterol biosynthesis (after squalene formation) special attention is paid to compounds possessing evident antifungal and antitumoral activity. Explanation of mechanism of anticancer and antiviral action of microbial ISB, as well as the description of their ability to induce apoptosis is given.

  17. Sterol 14alpha-demethylase (CYP51) as a therapeutic target for human trypanosomiasis and leishmaniasis.

    PubMed

    Lepesheva, Galina I; Waterman, Michael R

    2011-01-01

    Pathogenic protozoa threaten lives of several hundred million people throughout the world and are responsible for large numbers of deaths globally. The parasites are transmitted to humans by insect vectors, more than a hundred of infected mammalian species forming reservoir. With human migrations, HIV-coinfections, and blood bank contamination the diseases are now spreading beyond the endemic tropical countries, being found in all parts of the world including the USA, Canada and Europe. In spite of the widely appreciated magnitude of this health problem, current treatment for sleeping sickness (Trypanosoma brucei), Chagas disease (Trypanosoma cruzi) and leishmaniasis (Leishmania spp.) remains unsatisfactory. The drugs are decades old, their efficacy and safety profiles are unacceptable. This review describes sterol 14α-demethylase, an essential enzyme in sterol biosynthesis in eukaryotes and clinical target for antifungal azoles, as a promising target for antiprotozoan chemotherapy. While several antifungal azoles have been proven active against Trypanosomatidae and are under consideration as antiprotozoan agents, crystal structures of sterol 14α-demethylases from three protozoan pathogens, Trypanosoma brucei, Trypanosoma cruzi and Leishmania infantum provide the basis for the development of new, highly potent and pathogen-specific drugs with rationally optimized pharmacological properties.

  18. Correlation of neomycin, faecal neutral and acid sterols with colon carcinogenesis in rats

    PubMed Central

    Panda, S K; Chattoraj, S C; Broitman, S A

    1999-01-01

    High fat diets have been implicated in incidence of colon cancer both in epidemiological and animal studies. Present investigation deals with the incidence, location and numbers of large and small bowel tumours induced by 1,2-dimethyl hydrazine (DMH) in rats fed high fat diets and neomycin. Neomycin was used to modify the faecal sterol metabolism and the relationship of the high fat diet and faecal neutral and acid sterols to the large bowel tumorigenesis was evaluated. DMH administered rats were fed with (a) 20% safflower oil; (b) 20% safflower oil and neomycin; (c) 20% safflower oil, cholesterol and cholic acid; and (d) 20% safflower oil, cholesterol, cholic acid and neomycin. Neomycin was found to be associated with both increase and decrease of tumour numbers. The faecal sterols lithocholic and deoxycholic acids were found to have no participation, while cholesterol and cholic acid were found to decrease with increase in tumour numbers. However, faecal coprostanol has been found to have a significant positive correlation with tumorigenesis in all dietary groups. Therefore coprostanol might possibly be associated with colon carcinogenesis in DMH-fed rats and cholesterol metabolism in gut appears to be related to the development of tumours. © 1999 Cancer Research Campaign PMID:10376962

  19. Correlation of neomycin, faecal neutral and acid sterols with colon carcinogenesis in rats.

    PubMed

    Panda, S K; Chattoraj, S C; Broitman, S A

    1999-06-01

    High fat diets have been implicated in incidence of colon cancer both in epidemiological and animal studies. Present investigation deals with the incidence, location and numbers of large and small bowel tumours induced by 1,2-dimethyl hydrazine (DMH) in rats fed high fat diets and neomycin. Neomycin was used to modify the faecal sterol metabolism and the relationship of the high fat diet and faecal neutral and acid sterols to the large bowel tumorigenesis was evaluated. DMH administered rats were fed with (a) 20% safflower oil; (b) 20% safflower oil and neomycin; (c) 20% safflower oil, cholesterol and cholic acid; and (d) 20% safflower oil, cholesterol, cholic acid and neomycin. Neomycin was found to be associated with both increase and decrease of tumour numbers. The faecal sterols lithocholic and deoxycholic acids were found to have no participation, while cholesterol and cholic acid were found to decrease with increase in tumour numbers. However, faecal coprostanol has been found to have a significant positive correlation with tumorigenesis in all dietary groups. Therefore coprostanol might possibly be associated with colon carcinogenesis in DMH-fed rats and cholesterol metabolism in gut appears to be related to the development of tumours.

  20. Divergent changes in serum sterols during a strict uncooked vegan diet in patients with rheumatoid arthritis.

    PubMed

    Agren, J J; Tvrzicka, E; Nenonen, M T; Helve, T; Hänninen, O

    2001-02-01

    The effects of a strict uncooked vegan diet on serum lipid and sterol concentrations were studied in patients with rheumatoid arthritis. The subjects were randomized into a vegan diet group (n 16), who consumed a vegan diet for 2-3 months, or into a control group (n 13), who continued their usual omnivorous diets. Serum total and LDL-cholesterol and -phospholipid concentrations were significantly decreased by the vegan diet. The levels of serum cholestanol and lathosterol also decreased, but serum cholestanol:total cholesterol and lathosterol:total cholesterol did not change. The effect of a vegan diet on serum plant sterols was divergent as the concentration of campesterol decreased while that of sitosterol increased. This effect resulted in a significantly greater sitosterol:campesterol value in the vegan diet group than in the control group (1.48 (SD 0.39) v. 0.72 (SD 0.14); P < 0.001). A higher concentration of campesterol compared with sitosterol is normal in omnivorous subjects and can be explained by lower absorption and esterification rates of sitosterol. Our results suggest that a strict uncooked vegan diet changes the relative absorption rates of these sterols and/or their biliary clearance.

  1. Stationary phase lipophagy as a cellular mechanism to recycle sterols during quiescence.

    PubMed

    Wang, Chao-Wen

    2014-01-01

    Delivery of cellular contents to yeast vacuoles/mammalian lysosomes via autophagy ensures long-term cell survival and extends life span. When cultured yeast cells are grown for a prolonged period of time to enter stationary phase, a nondividing state mimicking quiescence, vacuolar membrane proteins partition into either one of the vacuolar microdomains, liquid-ordered (Lo) or liquid-disordered (Ld). We show that during the transition to stationary phase, lipid droplets (LDs), organelles originated from the endoplasmic reticulum (ER), undergo lateral movement to reach the vacuolar surface and are confined within the specific Lo microdomain underlying the network of vacuolar quasi-symmetrical micodomains. Stationary phase lipophagy uses the autophagy machineries to modify the sterol-enriched Lo microdomain to engulf LDs and subsequently deposits the LD-containing vesicles inside the vacuole lumen, which is a pathway morphologically resembling microautophagy. Moreover, stationary phase lipophagy supplies quiescent yeast cells with sterols to sustain phase partitioning of lipids for vacuolar microdomain maintenance. A feed forward loop model was proposed to depict that the sterols boosted by LDs via stationary phase lipophagy promote the Lo microdomain maintenance that in turn stimulates lipophagy.

  2. Oxysterol-binding proteins: sterol and phosphoinositide sensors coordinating transport, signaling and metabolism.

    PubMed

    Olkkonen, Vesa M; Li, Shiqian

    2013-10-01

    Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) constitute a family of sterol and phosphoinositide binding proteins conserved in eukaryotes. The mechanisms of ORP function have remained incompletely understood. However, several ORPs are present at membrane contact sites and control the activity of enzymatic effectors or assembly of protein complexes, with impacts on signaling, vesicle transport, and lipid metabolism. An increasing number of protein interaction partners of ORPs have been identified, providing clues of their involvement in multiple aspects of cell regulation. The functions assigned for mammalian ORPs include coordination of sterol and sphingolipid metabolism and mitogenic signaling (OSBP), control of ER-late endosome (LE) contacts and LE motility (ORP1L), neutral lipid metabolism (ORP2), cell adhesion (ORP3), cholesterol eggress from LE (ORP5), macrophage lipid homeostasis, migration and high-density lipoprotein metabolism (ORP8), apolipoprotein B-100 secretion (ORP10), and adipogenesis (ORP11). The anti-proliferative ORPphilin compounds target OSBP and ORP4, revealing a function of ORPs in cell proliferation and survival. The Saccharomyces cerevisiae OSBP homologue (Osh) proteins execute multifaceted functions in sterol and sphingolipid homeostasis, post-Golgi vesicle transport, as well as phosphatidylinositol-4-phosphate and target of rapamycin complex 1 (TORC1) signaling. These observations identify ORPs as coordinators of lipid signals with an unforeseen variety of cellular processes.

  3. Short-Term Water Deficit Changes Cuticular Sterol Profile in the Eggplant (Solanum melongena).

    PubMed

    Haliński, Łukasz P; Stepnowski, Piotr

    2016-06-01

    Crop irrigation uses a majority of a total world water supply, at the same time displaying low efficiency. As the expected, future water requirements are higher than the current ones; there is a risk of a growing deficit of water for the agricultural use. Hence, there is an arising need for better understanding the effects of water deprivation on the crop plants. Eggplant (Solanum melongena L.) is a vegetable crop cultivated in arid and semi-arid parts of the world. Because of its high water demands, the eggplant is a convenient model organism for studies concerning the effects of water deficit on the plant growth. The objective of the study was to determine the impact of short-term water deficit on eggplant leaf cuticular waxes and total sterols. Water deprivation did not affect the amount and composition of aliphatic components of cuticular waxes. Significant decrease in the total cuticular sterols and the increase in cuticular cholesterol were observed as an effect of water deficit. In contrast, some of the free internal sterols were more abundant in water-deprived plants. The possible importance of these observations, including increased biosynthesis of defensive compounds and the need to maintain the cell membrane stability, was discussed.

  4. Reactivity of key metabolic sterols in standard colorimetric assays for cholesterol.

    PubMed

    Sarkar, C P; Cenedella, R J

    1982-01-01

    The reaction of lanosterol, desmosterol and 7-dehydrocholesterol, key intermediates in cholesterol biosynthesis, were-compared with cholesterol in 3 standard colorimetric assays for cholesterol based on formation of chomogens with acetic anhydride, ferric chloride and ferrous sulfate. Marked differences in the reaction of the sterols in the different assays were due both to formation of chomogens with qualitatively similar spectral patterns but with greatly different extinctions and to formation of chromogens with clearly different absorption maxima. For example, in all assays, cholesterol and desmosterol formed chromogens with very similar absorption spectra but with varying extinctions, whereas the lanosterol chromogen in all assays was different from cholesterol's in both absorption maxima and in extinctions. The findings show that attempts to measure tissue sterol levels by colorimetric methods can result in greater errors when cholesterol is not the sole sterol. Also, the unique spectral properties of the lanosterol chromogen formed in the Liebermann-Burchard reaction (a sharp absorption peak at 450 nm) suggests the possible use of this method as a qualitative test for lanosterol.

  5. Dissolution of resin acids, retene and wood sterols from contaminated lake sediments.

    PubMed

    Meriläinen, Päivi; Lahdelma, Ilpo; Oikari, Laura; Hyötyläinen, Tarja; Oikari, Aimo

    2006-10-01

    The dissolution potency of hydrophobic resin acids (RAs), retene and wood sterols from sediments was studied. These wood extractives and their metabolites are sorbed from pulp and paper mill effluents to downstream sediments. With harmful components like these, sediments can pose a hazard to the aquatic environment. Therefore, sediment elutriates with water were produced under variable conditions (agitation rate and efficiency, time), and concentrations of the dissoluted compounds were analyzed. Both naturally contaminated field sediments and artificially spiked sediments were studied. By vigorous agitation RAs can be released fast from the sediment matrix and equilibrium reached within 3 days. Compared to RAs, desorption of retene from lake sediment was slower and did not completely reach equilibrium in 23 days. Sterols spiked to pristine sediment with a 33-day contact time desorbed faster than those associated authentically with industrial sediment of from a contaminated lake. Simulating the water turbulence adjacent to a sediment surface by low and high rate of agitation in the laboratory, an increase in the mixing rate after 43-day elutriation suddenly released a high amount of wood sterols. The results indicate wide variation between hazardous chemicals in their tendency to dissolution from sediment solids. Erosion and hydrology adjacent to the sediment surface, as well as risks from dredging activities of sediments, may expose lake biota to bioactive chemicals.

  6. Intracytoplasmic membrane, phospholipid, and sterol content of Methylobacterium organophilum cells grown under different conditions.

    PubMed Central

    Patt, T E; Hanson, R S

    1978-01-01

    Intracytoplasmic membranes were present in Methylobacterium organophilum when cells were grown with methane, but not methanol or glucose, as the sole carbon and energy source. Cells grown with methane as the carbon and energy source and low levels of dissolved oxygen had the greatest amount of intracytoplasmic membrane. Cells grown with increased levels of dissolved oxygen had less intracytoplasmic membrane. The amount of total lipid correlated with the amount of membrane material observed in thin sections. The individual phospholipids varied in amount, but the same four were present in M. organophilum grown with different substrates and oxygen levels. Phosphatidyl choline was present as a major component of the phospholipids. Sterols were present, and they differed from those in the type I methylotroph Methylococcus capsulatus. The relative amounts of different sterols and squalene changed with the substrate provided for growth. The greatest amounts of sterols were found in methane-grown cells grown at low levels of dissolved oxygen. None of the unusual or usual membrane components assayed was uniquely present in the intracytoplasmic membranes. Images PMID:96093

  7. Formulation and antifungal performance of natamycin-loaded liposomal suspensions: the benefits of sterol-enrichment.

    PubMed

    Bouaoud, Clotilde; Lebouille, Jérôme G J L; Mendes, Eduardo; De Braal, Henriette E A; Meesters, Gabriel M H

    2016-01-01

    The aim of this study is to develop and evaluate food-grade liposomal delivery systems for the antifungal compound natamycin. Liposomes made of various soybean lecithins are prepared by solvent injection, leading to small unilamellar vesicles (<130 nm) with controlled polydispersity, able to encapsulate natamycin without significant modification of their size characteristics. Presence of charged phospholipids and reduced content of phosphatidylcholine in the lecithin mixture are found to be beneficial for natamycin encapsulation, indicating electrostatic interactions of the preservative with the polar head of the phospholipids. The chemical instability of natamycin upon storage in these formulations is however significant and proves that uncontrolled leakage out of the liposomes occurs. Efficient prevention of natamycin degradation is obtained by incorporation of sterols (cholesterol, ergosterol) in the lipid mixture and is linked to higher entrapment levels and reduced permeability of the phospholipid membrane provided by the ordering effect of sterols. Comparable action of ergosterol is observed at concentrations 2.5-fold lower than cholesterol and attributed to a preferential interaction of natamycin-ergosterol as well as a higher control of membrane permeability. Fine-tuning of sterol concentration allows preparation of liposomal suspensions presenting modulated in vitro release kinetics rates and enhanced antifungal activity against the model yeast Saccharomyces cerevisiae.

  8. Distribution and sources of sterol biomarkers in sediments collected from a tropical estuary in Northeast Brazil.

    PubMed

    Frena, Morgana; Santos, Ana Paula Stein; Santos, Ewerton; Silva, Rosianne P; Souza, Michel R R; Madureira, Luiz A S; Alexandre, Marcelo R

    2016-11-01

    The Piauí-Real estuary is located along the southern coast of Sergipe state, Northeast Brazil. This estuary has great economic importance due to its physical, biological, and socioeconomic diversity, but it is subject to anthropogenic stress since the resident population in the town bordered by the estuarine system has grown in recent years. Thus, the possibility of sewage contamination originating from the approximately 450,000 inhabitants living within its drainage basin was investigated in this study. Sediment samples were collected from 15 sampling stations along the estuarine system and extracted, followed by gas chromatography-mass spectrometry (GC-MS) analysis. Six sterols were quantified, indicating natural and anthropogenic sources. Coprostanol concentrations higher than 100 ng g(-1) were observed in 47 % of the stations analyzed, indicating sewage contamination, which was confirmed by the diagnostic ratios calculated. Based on the Pearson correlation test, a significant correlation between coprostanol concentrations and total organic carbon content (TOC) was observed, indicating that sterols record the history of sewage inputs in this area. These results indicate that control of the organic inputs into the estuarine system is required. Graphical abstract Sterol markers were determined and sources assessed in surface sediments from Piauí-Real estuarine system.

  9. Insight into the mechanism for the methanol synthesis via the hydrogenation of CO2 over a Co-modified Cu(100) surface: A DFT study

    NASA Astrophysics Data System (ADS)

    Qiu, Mei; Tao, Huilin; Li, Rong; Li, Yi; Huang, Xin; Chen, Wenkai; Su, Wenyue; Zhang, Yongfan

    2016-10-01

    A comprehensive density functional theory calculation was employed to investigate the reaction mechanism of methanol synthesis on a Co-modified Cu(100) surface via CO2 hydrogenation. The Cu(100) surface with embedded small Co clusters prepared experimentally was employed as a model system to explore the effects of Co dopant on the catalytic performance of Cu(100) surface towards CH3OH synthesis. The activation energy barriers and the reaction energies of 16 elementary surface reactions were determined. Our calculated results show that the most favorable reaction pathway for the hydrogenation of CO2 to CH3OH follows the sequence of CO2 → HCOO* →H2COO* →H2COOH* →H2CO* →H3CO* →H3COH*, and the OH* group hydrogenation to H2 O* is the rate-limiting step with an activation barrier of 112.3 kJ/mol. It is noted that, since the strength of Co-O bond is stronger than that of Cu-O bond, the introducing of Co dopant on the Cu surface can facilitate the formation of key intermediates for the CH3OH synthesis. Especially, the stability of the unstable dioxomethylene intermediate (H2COO*) found on the pure Cu(100) surface can be obviously enhanced on the Co-doped Cu(100) surface. As a result, with respect to the undoped surface, the productivity and selectivity towards CH3OH production on the Cu(100) surface will be improved after dispersing small Co clusters on the surface.

  10. Enhancement of carotenoid production by disrupting the C22-sterol desaturase gene (CYP61) in Xanthophyllomyces dendrorhous

    PubMed Central

    2012-01-01

    Background Xanthophyllomyces dendrorhous is a basidiomycetous yeast that synthesizes astaxanthin, which is a carotenoid with a great biotechnological impact. The ergosterol and carotenoid synthesis pathways are derived from the mevalonate pathway, and in both pathways, cytochrome P450 enzymes are involved. Results In this study, we isolated and described the X. dendrorhous CYP61 gene, which encodes a cytochrome P450 involved in ergosterol biosynthesis. This gene is composed of nine exons and encodes a 526 amino acid polypeptide that shares significant percentages of identity and similitude with the C22-sterol desaturase, CYP61, from other fungi. Mutants derived from different parental strains were obtained by disrupting the CYP61 gene with an antibiotic selection marker. These mutants were not able to produce ergosterol and accumulated ergosta-5,8,22-trien-3-ol and ergosta-5,8-dien-3-ol. Interestingly, all of the mutants had a more intense red color phenotype than their respective parental strains. The carotenoid composition was qualitatively and quantitatively analyzed by RP-HPLC, revealing that the carotenoid content was higher in the mutant strains without major changes in their composition. The expression of the HMGR gene, which encodes an enzyme involved in the mevalonate pathway (3-hydroxy-3-methylglutaryl-CoA reductase), was analyzed by RT-qPCR showing that its transcript levels are higher in the CYP61 mutants. Conclusions These results suggest that in X. dendrorhous, ergosterol regulates HMGR gene expression by a negative feedback mechanism and in this way; it contributes in the regulation of the carotenoid biosynthesis. PMID:23075035

  11. A novel fibrosis index comprising a non-cholesterol sterol accurately predicts HCV-related liver cirrhosis.

    PubMed

    Ydreborg, Magdalena; Lisovskaja, Vera; Lagging, Martin; Brehm Christensen, Peer; Langeland, Nina; Buhl, Mads Rauning; Pedersen, Court; Mørch, Kristine; Wejstål, Rune; Norkrans, Gunnar; Lindh, Magnus; Färkkilä, Martti; Westin, Johan

    2014-01-01

    Diagnosis of liver cirrhosis is essential in the management of chronic hepatitis C virus (HCV) infection. Liver biopsy is invasive and thus entails a risk of complications as well as a potential risk of sampling error. Therefore, non-invasive diagnostic tools are preferential. The aim of the present study was to create a model for accurate prediction of liver cirrhosis based on patient characteristics and biomarkers of liver fibrosis, including a panel of non-cholesterol sterols reflecting cholesterol synthesis and absorption and secretion. We evaluated variables with potential predictive significance for liver fibrosis in 278 patients originally included in a multicenter phase III treatment trial for chronic HCV infection. A stepwise multivariate logistic model selection was performed with liver cirrhosis, defined as Ishak fibrosis stage 5-6, as the outcome variable. A new index, referred to as Nordic Liver Index (NoLI) in the paper, was based on the model: Log-odds (predicting cirrhosis) = -12.17+ (age × 0.11) + (BMI (kg/m(2)) × 0.23) + (D7-lathosterol (μg/100 mg cholesterol)×(-0.013)) + (Platelet count (x10(9)/L) × (-0.018)) + (Prothrombin-INR × 3.69). The area under the ROC curve (AUROC) for prediction of cirrhosis was 0.91 (95% CI 0.86-0.96). The index was validated in a separate cohort of 83 patients and the AUROC for this cohort was similar (0.90; 95% CI: 0.82-0.98). In conclusion, the new index may complement other methods in diagnosing cirrhosis in patients with chronic HCV infection.

  12. Tracing the Temporal and Spatial Variations in the Origin of Fecal Material in Three Oklahoma Watersheds Using Sterol Fingerprints

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Philp, P. R.

    2014-12-01

    Organic wastes, in particular fecal material, are qualified as one of the major causes of water quality deterioration. Their accumulation in water bodies may increase algal proliferation and eutrophication and the number of pathogenic organisms, which are responsible for many intestinal diseases especially when the water is used for recreational activities and/or as a supply for drinking water. In order to estimate the risk level associated with primary body contact in recreational water bodies, enumeration of some specific micro-organisms, such as Enterococci and Escherichia coli, are commonly used. Sterol distributions can provide some relevant information on the origin of fecal material in water system, since they are ubiquitous organic compounds and their distributions in many warm-blooded animal feces can be used as evidence for their source. In this study, we monitored fecal material contamination in three Oklahoma watersheds based on sterol fingerprints over a one-year period (2012 ~ 2013). The sterols from sediments and water samples (sterols associated to suspended particles as well as free sterols in water) were recovered using sonication and solid phase extraction (SPE), respectively, using different organic solvents. They were then identified and quantified by gas chromatography - mass spectrometry (GC-MS) using an internal standard. The GC-MS was previously calibrated with a sterol mixture injected at different concentrations. Our primary results show that the concentration of total sterols generally increases from the Upper Canadian < Neosho Grand < Cimarron - Upper Arkansas Basins in Oklahoma. The fecal sterols commonly represent a small proportion (<15%) within the total sterols quantified in these three basins. Their distributions show a significant contribution from herbivore feces. By means of this monitoring, we are able to determine the presence of fecal contamination and provide a better understanding on the ability of using sterol

  13. Relationship of the neutral sterols and ecdysteroids of the parasitic mite, Varroa jacobsoni to those of the honey bee, Apis mellifera.

    PubMed

    Hartfelder, K; Feldlaufer, M F.

    1997-06-01

    The neutral sterols of the parasitic mite Varroa jacobsoni were compared with Apis mellifera carnica drone pupae. Analysis by GLC-mass spectrometry indicated mite sterols were reflective of the sterol composition of the drones; 24-methylenecholesterol was the major sterol in both species, with lesser amounts of sitosterol and isofucosterol. Cholesterol accounted for less than 1% of the total sterols. Ecdysteroid analyses indicated drones contained primarily makisterone A. In addition to makisterone A, mites contained ecdysone and 20-hydroxyecdysone, which accounted for over 66% of the ecdysteroid detected. These results indicate that while V. jacobsoni are apparently unable to convert dietary sterols to cholesterol, they are able to produce significant amount of C(27) ecdysteroids in a low cholesterol environment.

  14. Insights into the Role of Specific Lipids in the Formation and Delivery of Lipid Microdomains to the Plasma Membrane of Plant Cells1[W

    PubMed Central

    Laloi, Maryse; Perret, Anne-Marie; Chatre, Laurent; Melser, Su; Cantrel, Catherine; Vaultier, Marie-Noëlle; Zachowski, Alain; Bathany, Katell; Schmitter, Jean-Marie; Vallet, Myriam; Lessire, René; Hartmann, Marie-Andrée; Moreau, Patrick

    2007-01-01

    The existence of sphingolipid- and sterol-enriched microdomains, known as lipid rafts, in the plasma membrane (PM) of eukaryotic cells is well documented. To obtain more insight into the lipid molecular species required for the formation of microdomains in plants, we have isolated detergent (Triton X-100)-resistant membranes (DRMs) from the PM of Arabidopsis (Arabidopsis thaliana) and leek (Allium porrum) seedlings as well as from Arabidopsis cell cultures. Here, we show that all DRM preparations are enriched in sterols, sterylglucosides, and glucosylceramides (GluCer) and depleted in glycerophospholipids. The GluCer of DRMs from leek seedlings contain hydroxypalmitic acid. We investigated the role of sterols in DRM formation along the secretory pathway in leek seedlings. We present evidence for the presence of DRMs in both the PM and the Golgi apparatus but not in the endoplasmic reticulum. In leek seedlings treated with fenpropimorph, a sterol biosynthesis inhibitor, the usual Δ5-sterols are replaced by 9β,19-cyclopropylsterols. In these plants, sterols and hydroxypalmitic acid-containing GluCer do not reach the PM, and most DRMs are recovered from the Golgi apparatus, indicating that Δ5-sterols and GluCer play a crucial role in lipid microdomain formation and delivery to the PM. In addition, DRM formation in Arabidopsis cells is shown to depend on the unsaturation degree of fatty acyl chains as evidenced by the dramatic decrease in the amount of DRMs prepared from the Arabidopsis mutants, fad2 and Fad3+, affected in their fatty acid desaturases. PMID:17114270

  15. Insight into the Ligand-Mediated Synthesis of Colloidal CsPbBr3 Perovskite Nanocrystals: The Role of Organic Acid, Base, and Cesium Precursors.

    PubMed

    Pan, Aizhao; He, Bo; Fan, Xiaoyun; Liu, Zeke; Urban, Jeffrey J; Alivisatos, A Paul; He, Ling; Liu, Yi

    2016-08-23

    While convenient solution-based procedures have been realized for the synthesis of colloidal perovskite nanocrystals, the impact of surfactant ligands on the shape, size, and surface properties still remains poorly understood, which calls for a more detailed structure-morphology study. Herein we have systematically varied the hydrocarbon chain composition of carboxylic acids and amines to investigate the surface chemistry and the independent impact of acid and amine on the size and shape of perovskite nanocrystals. Solution phase studies on purified nanocrystal samples by (1)H NMR and IR spectroscopies have confirmed the presence of both carboxylate and alkylammonium ligands on surfaces, with the alkylammonium ligand being much more mobile and susceptible to detachment from the nanocrystal surfaces during polar solvent washes. Moreover, the chain length variation of carboxylic acids and amines, ranging from 18 carbons down to two carbons, has shown independent correlation to the size and shape of nanocrystals in addition to the temperature effect. We have additionally demonstrated that employing a more soluble cesium acetate precursor in place of the universally used Cs2CO3 results in enhanced processability without sacrificing optical properties, thus offering a more versatile recipe for perovskite nanocrystal synthesis that allows the use of organic acids and amines bearing chains shorter than eight carbon atoms. Overall our studies have shed light on the influence of ligand chemistry on crystal growth and stabilization of the nanocrystals, which opens the door to functionalizable perovskite nanocrsytals through surface ligand manipulation.

  16. Vaginal birth after caesarean section: why is uptake so low? Insights from a meta-ethnographic synthesis of women's accounts of their birth choices

    PubMed Central

    Black, Mairead; Entwistle, Vikki A; Bhattacharya, Siladitya; Gillies, Katie

    2016-01-01

    Objective To identify what women report influences their preferred mode of birth after caesarean section. Design Systematic review of qualitative literature using meta-ethnography. Data sources Medline, EMBASE, ASSIA, CINAHL and PsycINFO (1996 until April 2013; updated September 2015). Hand-searched journals, reference lists and abstract authors. Study selection Primary qualitative studies reporting women's accounts of what influenced their preferred mode of birth after caesarean section. Data extraction and synthesis Primary data (quotations from study participants) and authors’ interpretations of these were extracted, compared and contrasted between studies, and grouped into themes to support the development of a ‘line of argument’ synthesis. Results 20 papers reporting the views of 507 women from four countries were included. Distinctive clusters of influences were identified for each of three groups of women. Women who confidently sought vaginal birth after a caesarean section were typically driven by a long-standing anticipation of vaginal birth. Women who sought a repeat caesarean section were strongly influenced by distressing previous birth experiences, and at times, by encouragement from social contacts. Women who were more open to information and professional guidance had fewer strong preconceptions and concerns, and viewed a range of considerations as potentially important. Conclusions Women's attitudes towards birth after caesarean section appear to be shaped by distinct clusters of influences, suggesting that opportunities exist for clinicians to stratify and personalise decision support by addressing relevant ideas, concerns and experiences from the first caesarean section birth onwards. PMID:26747030

  17. Overexpression of ALDH10A8 and ALDH10A9 Genes Provides Insight into Their Role in Glycine Betaine Synthesis and Affects Primary Metabolism in Arabidopsis thaliana.

    PubMed

    Missihoun, Tagnon D; Willée, Eva; Guegan, Jean-Paul; Berardocco, Solenne; Shafiq, Muhammad R; Bouchereau, Alain; Bartels, Dorothea

    2015-09-01

    Betaine aldehyde dehydrogenases oxidize betaine aldehyde to glycine betaine in species that accumulate glycine betaine as a compatible solute under stress conditions. In contrast, the physiological function of betaine aldehyde dehydrogenase genes is at present unclear in species that do not accumulate glycine betaine, such as Arabidopsis thaliana. To address this question, we overexpressed the Arabidopsis ALDH10A8 and ALDH10A9 genes, which were identified to code for betaine aldehyde dehydrogenases, in wild-type A. thaliana. We analysed changes in metabolite contents of transgenic plants in comparison with the wild type. Using exogenous or endogenous choline, our results indicated that ALDH10A8 and ALDH10A9 are involved in the synthesis of glycine betaine in Arabidopsis. Choline availability seems to be a factor limiting glycine betaine synthesis. Moreover, the contents of diverse metabolites including sugars (glucose and fructose) and amino acids were altered in fully developed transgenic plants compared with the wild type. The plant metabolic response to salt and the salt stress tolerance were impaired only in young transgenic plants, which exhibited a delayed growth of the seedlings early after germination. Our results suggest that a balanced expression of the betaine aldehyde dehydrogenase genes is important for early growth of A. thaliana seedlings and for salt stress mitigation in young seedlings.

  18. A highly specific and sensitive quantification analysis of the sterols in silkworm larvae by high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

    PubMed

    Igarashi, Fumihiko; Hikiba, Juri; Ogihara, Mari H; Nakaoka, Takayoshi; Suzuki, Minoru; Kataoka, Hiroshi

    2011-12-15

    The biochemical quantification of sterols in insects has been difficult because only small amounts of tissues can be obtained from insect bodies and because sterol metabolites are structurally related. We have developed a highly specific and sensitive quantitative method for determining of the concentrations of seven sterols-7-dehydrocholesterol, desmosterol, cholesterol, ergosterol, campesterol, stigmasterol, and β-sitosterol-using a high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC/APCI-MS/MS). The sterols were extracted from silkworm larval tissues using the Bligh and Dyer method and were analyzed using HPLC/APCI-MS/MS with selected reaction monitoring, using cholesterol-3,4-(13)C(2) as an internal standard. The detection limits of the method were between 12.1 and 259 fmol. The major sterol in most silkworm larval tissues was cholesterol, whereas only small quantities of the dietary sterols were detected. Thus, a simple, sensitive, and specific method was successfully developed for the quantification of the sterol concentrations in each tissue of an individual silkworm larva. This method will be a useful tool for investigating to molecular basis of sterol physiology in insects, facilitating the quantification of femtomole quantities of sterols in biological samples.

  19. Light-assisted synthesis and functionalization of silver nanoparticles with thiol derivative thioxanthones: new insights into the engineering of metal/chromophore nanoassemblies

    NASA Astrophysics Data System (ADS)

    Niu, Songlin; Schneider, Raphaël; Vidal, Loïc; Hajjar-Garreau, Samar; Balan, Lavinia

    2014-09-01

    In this study, silver nanoparticles (Ag NPs) were generated, functionalized, and stabilized using a one-step photochemical approach that does not require more than few minutes with a low power near UV LED source. A series of thiol-functionalized thioxanthone (TX) derivatives were prepared and used for the photoinduced synthesis of Ag NPs and their surface functionalization and stabilization. Upon illumination, Ag+ ions are reduced by free radicals generated through an oxidoreductive process occurring between excited TX groups and N-methyldiethanolamine. This process generates monodispersed silver nanoparticles with an average diameter about 2-7 nm depending on the TX derivative used. Due to the strong interaction between Ag atoms and thiol groups of the ligands, AgNPs are capped in situ by TX derivatives and exhibit remarkable stability in solution. Subsequent studies carried out on silver NPs/TX nanoassemblies (designed as AgNPs@S-TX) demonstrated their potentials in free radical photopolymerization of acrylate monomers.

  20. Imidazolium Sulfonates as Environmental-Friendly Catalytic Systems for the Synthesis of Biologically Active 2-Amino-4H-chromenes: Mechanistic Insights.

    PubMed

    Velasco, Jacinto; Pérez-Mayoral, Elena; Calvino-Casilda, Vanesa; López-Peinado, Antonio J; Bañares, Miguel A; Soriano, Elena

    2015-09-10

    Ionic Liquids (ILs) are valuable reaction media extremely useful in industrial sustainable organic synthesis. We describe here the study on the multicomponent reaction (MCR) between salicylaldehyde (2) and ethyl cyanoacetate (3), catalyzed by imidazolium sulfonates, to form chromenes 1, a class of heterocyclic scaffolds exhibiting relevant biological activity. We have clarified the reaction mechanism by combining the experimental results with computational studies. The results reported herein suggest that both the imidazolium core and the sulfonate anions in the selected ILs are involved in the reaction course acting as hydrogen bond donors and acceptors, respectively. Contrarily to the most widely accepted mechanism through initial Knoevenagel condensation, the most favorable reaction pathway consists of an aldolic reaction between reagents followed by heterocyclization, subsequent dehydration, and, finally, the Michael addition of the second molecule of ethyl cyanoacetate (3) to yield the chromenes 1.

  1. High-resolution structures of Neotermes koshunensis β-glucosidase mutants provide insights into the catalytic mechanism and the synthesis of glucoconjugates.

    PubMed

    Jeng, Wen-Yih; Wang, Nai-Chen; Lin, Cheng-Tse; Chang, Wei-Jung; Liu, Chia-I; Wang, Andrew H-J

    2012-07-01

    NkBgl, a β-glucosidase from Neotermes koshunensis, is a β-retaining glycosyl hydrolase family 1 enzyme that cleaves β-glucosidic linkages in disaccharide or glucose-substituted molecules. β-Glucosidases have been widely used in several applications. For example, mutagenesis of the attacking nucleophile in β-glucosidase has been conducted to convert it into a glycosynthase for the synthesis of oligosaccharides. Here, several high-resolution structures of wild-type or mutated NkBgl in complex with different ligand molecules are reported. In the wild-type NkBgl structures it was found that glucose-like glucosidase inhibitors bind to the glycone-binding pocket, allowing the buffer molecule HEPES to remain in the aglycone-binding pocket. In the crystal structures of NkBgl E193A, E193S and E193D mutants Glu193 not only acts as the catalytic acid/base but also plays an important role in controlling substrate entry and product release. Furthermore, in crystal structures of the NkBgl E193D mutant it was found that new glucoconjugates were generated by the conjugation of glucose (hydrolyzed product) and HEPES/EPPS/opipramol (buffer components). Based on the wild-type and E193D-mutant structures of NkBgl, the glucosidic bond of cellobiose or salicin was hydrolyzed and a new bond was subsequently formed between glucose and HEPES/EPPS/opipramol to generate new glucopyranosidic products through the transglycosylation reaction in the NkBgl E193D mutant. This finding highlights an innovative way to further improve β-glucosidases for the enzymatic synthesis of oligosaccharides.

  2. Interaction between the marine sponge cyclic peptide theonellamide A and sterols in lipid bilayers as viewed by surface plasmon resonance and solid-state (2)H nuclear magnetic resonance.

    PubMed

    Espiritu, Rafael Atillo; Matsumori, Nobuaki; Murata, Michio; Nishimura, Shinichi; Kakeya, Hideaki; Matsunaga, Shigeki; Yoshida, Minoru

    2013-04-09

    Theonellamides (TNMs) are members of a distinctive family of antifungal and cytotoxic bicyclic dodecapeptides isolated from the marine sponge Theonella sp. Recently, it has been shown that TNMs recognize 3β-hydroxysterol-containing membranes, induce glucan overproduction, and damage cellular membranes. However, to date, the detailed mode of sterol binding at a molecular level has not been determined. In this study, to gain insight into the mechanism of sterol recognition of TNM in lipid bilayers, surface plasmon resonance (SPR) experiments and solid-state deuterium nuclear magnetic resonance ((2)H NMR) measurements were performed on theonellamide A (TNM-A). SPR results revealed that the incorporation of 10 mol % cholesterol or ergosterol into 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes significantly enhances the affinity of the peptide for the membrane, particularly in the initial binding to the membrane surface. These findings, together with the fact that binding of TNM-A to epicholesterol (3α-cholesterol)-containing liposomes and pure POPC liposomes was comparably weak, confirmed the preference of the peptide for the 3β-hydroxysterol-containing membranes. To further establish the formation of the complex of TNM-A with 3β-hydroxysterols in lipid bilayers, solid-state (2)H NMR measurements were conducted using deuterium-labeled cholesterol, ergosterol, or epicholesterol. The (2)H NMR spectra showed that TNM-A significantly inhibits the fast rotational motion of cholesterol and ergosterol, but not epicholesterol, therefore verifying the direct complexation between TNM-A and 3β-hydroxysterols in lipid bilayers. This study demonstrates that TNM-A directly recognizes the 3β-OH moiety of sterols, which greatly facilitates its binding to bilayer membranes.

  3. Rapid synthesis of hybrids and hollow PdO nanostructures by controlled in situ dissolution of a ZnO nanorod template: insights into the formation mechanism and thermal stability

    NASA Astrophysics Data System (ADS)

    Kundu, Subhajit; Ravishankar, N.

    2016-01-01

    Hollow nanomaterials have attracted a lot of interest by virtue of their wide range of applications that arise primarily due to their unique architecture. A common strategy to synthesize hollow nanomaterials is by nucleation of the shell material over a preformed core and subsequent dissolution of the core in the second step. Herein an ultrafast, microwave route has been demonstrated, to synthesize PdO nanotubes in a single step using ZnO as a sacrificial template. The mechanism of the nanotube formation has been investigated in detail using control experiments. By tuning the starting ratio of PdCl2 : ZnO, hollow to hybrid PdO nanostructures could be obtained using the same method. Conversion of the PdO to Pd nanotubes has been shown by simple NaBH4 treatment. The thermal stability of the PdO nanotubes has been studied. The insights presented here are general and applicable for the synthesis of hybrids/hollow structures in other systems as well.Hollow nanomaterials have attracted a lot of interest by virtue of their wide range of applications that arise primarily due to their unique architecture. A common strategy to synthesize hollow nanomaterials is by nucleation of the shell material over a preformed core and subsequent dissolution of the core in the second step. Herein an ultrafast, microwave route has been demonstrated, to synthesize PdO nanotubes in a single step using ZnO as a sacrificial template. The mechanism of the nanotube formation has been investigated in detail using control experiments. By tuning the starting ratio of PdCl2 : ZnO, hollow to hybrid PdO nanostructures could be obtained using the same method. Conversion of the PdO to Pd nanotubes has been shown by simple NaBH4 treatment. The thermal stability of the PdO nanotubes has been studied. The insights presented here are general and applicable for the synthesis of hybrids/hollow structures in other systems as well. Electronic supplementary information (ESI) available: Details of experiments

  4. Acyl-CoA:cholesterol acyltransferases (ACATs/SOATs): Enzymes with multiple sterols as substrates and as activators.

    PubMed

    Rogers, Maximillian A; Liu, Jay; Song, Bao-Liang; Li, Bo-Liang; Chang, Catherine C Y; Chang, Ta-Yuan

    2015-07-01

    Cholesterol is essential to the growth and viability of cells. The metabolites of cholesterol include: steroids, oxysterols, and bile acids, all of which play important physiological functions. Cholesterol and its metabolites have been implicated in the pathogenesis of multiple human diseases, including: atherosclerosis, cancer, neurodegenerative diseases, and diabetes. Thus, understanding how cells maintain the homeostasis of cholesterol and its metabolites is an important area of study. Acyl-coenzyme A:cholesterol acyltransferases (ACATs, also abbreviated as SOATs) converts cholesterol to cholesteryl esters and play key roles in the regulation of cellular cholesterol homeostasis. ACATs are most unusual enzymes because (i) they metabolize diverse substrates including both sterols and certain steroids; (ii) they contain two different binding sites for steroidal molecules. In mammals, there are two ACAT genes that encode two different enzymes, ACAT1 and ACAT2. Both are allosteric enzymes that can be activated by a variety of sterols. In addition to cholesterol, other sterols that possess the 3-beta OH at C-3, including PREG, oxysterols (such as 24(S)-hydroxycholesterol and 27-hydroxycholesterol, etc.), and various plant sterols, could all be ACAT substrates. All sterols that possess the iso-octyl side chain including cholesterol, oxysterols, various plant sterols could all be activators of ACAT. PREG can only be an ACAT substrate because it lacks the iso-octyl side chain required to be an ACAT activator. The unnatural cholesterol analogs epi-cholesterol (with 3-alpha OH in steroid ring B) and ent-cholesterol (the mirror image of cholesterol) contain the iso-octyl side chain but do not have the 3-beta OH at C-3. Thus, they can only serve as activators and cannot serve as substrates. Thus, within the ACAT holoenzyme, there are site(s) that bind sterol as substrate and site(s) that bind sterol as activator; these sites are distinct from each other. These features form

  5. Fermentation of soybean oil deodorizer distillate with Candida tropicalis to concentrate phytosterols and to produce sterols-rich yeast cells.

    PubMed

    Zhao, Guoqun; Hu, Tao; Zhao, Lihua

    2014-03-01

    Phytosterols have been recovered from the deodorizer distillate produced in the final deodorization step of vegetable oil refining by various processes. The deodorizer distillate contains mainly free fatty acids (FFAs), phytosterols, and tocopherols. The presence of FFAs hinders recovery of phytosterols. In this study, fermentation of soybean oil deodorizer distillate (SODD) with Candida tropicalis 1253 was carried out. FFAs were utilized as carbon source and converted into cellular components as the yeast cells grew. Phytosterols concentration in SODD increased from 15.2 to 28.43 % after fermentation. No significant loss of phytosterols was observed during the process. Microbial fermentation of SODD is a potential approach to concentrate phytosterols before the recovery of phytosterols from SODD. During SODD fermentation, sterols-rich yeast cells were produced and the content of total sterols was as high as 6.96 %, but its major sterol was not ergosterol, which is the major sterol encountered in Saccharomyces cerevisiae. Except ergosterol, other sterols synthesized in the cells need to be identified.

  6. Accumulation of specific sterol precursors targets a MAP kinase cascade mediating cell-cell recognition and fusion.

    PubMed

    Weichert, Martin; Lichius, Alexander; Priegnitz, Bert-Ewald; Brandt, Ulrike; Gottschalk, Johannes; Nawrath, Thorben; Groenhagen, Ulrike; Read, Nick D; Schulz, Stefan; Fleißner, André

    2016-10-18

    Sterols are vital components of eukaryotic cell membranes. Defects in sterol biosynthesis, which result in the accumulation of precursor molecules, are commonly associated with cellular disorders and disease. However, the effects of these sterol precursors on the metabolism, signaling, and behavior of cells are only poorly understood. In this study, we show that the accumulation of only ergosterol precursors with a conjugated double bond in their aliphatic side chain specifically disrupts cell-cell communication and fusion in the fungus Neurospora crassa Genetically identical germinating spores of this fungus undergo cell-cell fusion, thereby forming a highly interconnected supracellular network during colony initiation. Before fusion, the cells use an unusual signaling mechanism that involves the coordinated and alternating switching between signal sending and receiving states of the two fusion partners. Accumulation of only ergosterol precursors with a conjugated double bond in their aliphatic side chain disrupts this coordinated cell-cell communication and suppresses cell fusion. These specific sterol precursors target a single ERK-like mitogen-activated protein (MAP) kinase (MAK-1)-signaling cascade, whereas a second MAP kinase pathway (MAK-2), which is also involved in cell fusion, is unaffected. These observations indicate that a minor specific change in sterol structure can exert a strong detrimental effect on a key signaling pathway of the cell, resulting in the absence of cell fusion.

  7. Kinetics of template-directed pyrophosphate-linked dideoxyguanylate synthesis as a function of 2-MeImpdG and poly(C) concentration: insights into the mechanism

    NASA Technical Reports Server (NTRS)

    Kanavarioti, A.; Gangopadhyay, S.

    1999-01-01

    Aqueous solutions of deoxyguanosine 5'-monophosphate 2-methylimidazolide, 2-MeImpdG, yield primarily deoxyguanosine 5'-monophosphate, 5'dGMP, and pyrophosphate-linked dideoxyguanylate, dG5'ppdG, abbreviated G2p (see Chart 1). The initial rate of G2p formation, d[G2p]/dt in M h-1, determined at 23 degrees C, pH 7.8, 1.0 M NaCl and 0.2 M Mg2+ by timed high-performance liquid chromatography (HPLC) analysis, exhibits a second-order dependence on 2-MeImpdG concentration, [G]o, indicating a bimolecular mechanism of dimerization in the range 0.02 M < or = [G]o < or = 0.09 M. In the presence of polycytidylate, poly(C), G2p synthesis is accelerated and oligodeoxyguanylate products are formed by incorporation of 2-MeImpdG molecules. The kinetics of G2p formation as a function of both monomer and polymer concentration, expressed in C equivalents, were also determined under the above conditions and exhibited a complex behavior. Specifically, at a constant [poly(C)], values of d[G2p]/dt typically increased with [G]o with a parabolic upward curvature. At a constant [G]o, values of d[G2p]/dt increase with [poly(C)], but level off at the higher poly(C) concentrations. As [G]o increases this saturation occurs at a higher poly(C) concentration, a result opposite to expectation for a simple complexation of two reacting monomers with the catalyst prior to reaction. Nevertheless, these results are shown to be quantitatively consistent with a template-directed (TD) mechanism of dimerization where poly(C) acts as the template to bind 2-MeImpdG in a cooperative manner and lead, for the first time, to the formulation of principles that govern template-directed chemistry. Analysis of the kinetic data via a proposed TD cooperative model provides association constants for the affinity between polymer and monomer and the intrinsic reactivity of 2-MeImpdG toward pyrophosphate synthesis. To the best of our knowledge, poly(C)/2-MeImpdG is the first system that could serve as a textbook example of

  8. New insights into selective heterogeneous nucleation of metal nanoparticles on oxides by microwave-assisted reduction: rapid synthesis of high-activity supported catalysts.

    PubMed

    Anumol, Erumpukuthickal Ashok; Kundu, Paromita; Deshpande, Parag Arvind; Madras, Giridhar; Ravishankar, Narayanan

    2011-10-25

    Microwave-based methods are widely employed to synthesize metal nanoparticles on various substrates. However, the detailed mechanism of formation of such hybrids has not been addressed. In this paper, we describe the thermodynamic and kinetic aspects of reduction of metal salts by ethylene glycol under microwave heating conditions. On the basis of this analysis, we identify the temperatures above which the reduction of the metal salt is thermodynamically favorable and temperatures above which the rates of homogeneous nucleation of the metal and the heterogeneous nucleation of the metal on supports are favored. We delineate different conditions which favor the heterogeneous nucleation of the metal on the supports over homogeneous nucleation in the solvent medium based on the dielectric loss parameters of the solvent and the support and the metal/solvent and metal/support interfacial energies. Contrary to current understanding, we show that metal particles can be selectively formed on the substrate even under situations where the temperature of the substrate is lower than that of the surrounding medium. The catalytic activity of the Pt/CeO(2) and Pt/TiO(2) hybrids synthesized by this method for H(2) combustion reaction shows that complete conversion is achieved at temperatures as low as 100 °C with Pt-CeO(2) catalyst and at 50 °C with Pt-TiO(2) catalyst. Our method thus opens up possibilities for rational synthesis of high-activity supported catalysts using a fast microwave-based reduction method.

  9. Targeting brain serotonin synthesis: insights into neurodevelopmental disorders with long-term outcomes related to negative emotionality, aggression and antisocial behaviour.

    PubMed

    Lesch, Klaus-Peter; Araragi, Naozumi; Waider, Jonas; van den Hove, Daniel; Gutknecht, Lise

    2012-09-05

    Aggression, which comprises multi-faceted traits ranging from negative emotionality to antisocial behaviour, is influenced by an interaction of biological, psychological and social variables. Failure in social adjustment, aggressiveness and violence represent the most detrimental long-term outcome of neurodevelopmental disorders. With the exception of brain-specific tryptophan hydroxylase-2 (Tph2), which generates serotonin (5-HT) in raphe neurons, the contribution of gene variation to aggression-related behaviour in genetically modified mouse models has been previously appraised (Lesch 2005 Novartis Found Symp. 268, 111-140; Lesch & Merschdorf 2000 Behav. Sci. Law 18, 581-604). Genetic inactivation of Tph2 function in mice led to the identification of phenotypic changes, ranging from growth retardation and late-onset obesity, to enhanced conditioned fear response, increased aggression and depression-like behaviour. This spectrum of consequences, which are amplified by stress-related epigenetic interactions, are attributable to deficient brain 5-HT synthesis during development and adulthood. Human data relating altered TPH2 function to personality traits of negative emotionality and neurodevelopmental disorders characterized by deficits in cognitive control and emotion regulation are based on genetic association and are therefore not as robust as the experimental mouse results. Mouse models in conjunction with approaches focusing on TPH2 variants in humans provide unexpected views of 5-HT's role in brain development and in disorders related to negative emotionality, aggression and antisocial behaviour.

  10. Synthesis, biological activity and mechanistic insights of 1-substituted cyclopropylamine derivatives: a novel class of irreversible inhibitors of histone demethylase KDM1A.

    PubMed

    Vianello, Paola; Botrugno, Oronza A; Cappa, Anna; Ciossani, Giuseppe; Dessanti, Paola; Mai, Antonello; Mattevi, Andrea; Meroni, Giuseppe; Minucci, Saverio; Thaler, Florian; Tortorici, Marcello; Trifiró, Paolo; Valente, Sergio; Villa, Manuela; Varasi, Mario; Mercurio, Ciro

    2014-10-30

    Histone demethylase KDM1A (also known as LSD1) has become an attractive therapeutic target for the treatment of cancer as well as other disorders such as viral infections. We report on the synthesis of compounds derived from the expansion of tranylcypromine as a chemical scaffold for the design of novel demethylase inhibitors. These compounds, which are substituted on the cyclopropyl core moiety, were evaluated for their ability to inhibit KDM1A in vitro as well as to function in cells by modulating the expression of Gfi-1b, a well recognized KDM1A target gene. The molecules were all found to covalently inhibit KDM1A and to become increasingly selective against human monoamine oxidases MAO A and MAO B through the introduction of bulkier substituents on the cyclopropylamine ring. Structural and biochemical analysis of selected trans isomers showed that the two stereoisomers are endowed with similar inhibitory activities against KDM1A, but form different covalent adducts with the FAD co-enzyme.

  11. Targeting brain serotonin synthesis: insights into neurodevelopmental disorders with long-term outcomes related to negative emotionality, aggression and antisocial behaviour

    PubMed Central

    Lesch, Klaus-Peter; Araragi, Naozumi; Waider, Jonas; van den Hove, Daniel; Gutknecht, Lise

    2012-01-01

    Aggression, which comprises multi-faceted traits ranging from negative emotionality to antisocial behaviour, is influenced by an interaction of biological, psychological and social variables. Failure in social adjustment, aggressiveness and violence represent the most detrimental long-term outcome of neurodevelopmental disorders. With the exception of brain-specific tryptophan hydroxylase-2 (Tph2), which generates serotonin (5-HT) in raphe neurons, the contribution of gene variation to aggression-related behaviour in genetically modified mouse models has been previously appraised (Lesch 2005 Novartis Found Symp. 268, 111–140; Lesch & Merschdorf 2000 Behav. Sci. Law 18, 581–604). Genetic inactivation of Tph2 function in mice led to the identification of phenotypic changes, ranging from growth retardation and late-onset obesity, to enhanced conditioned fear response, increased aggression and depression-like behaviour. This spectrum of consequences, which are amplified by stress-related epigenetic interactions, are attributable to deficient brain 5-HT synthesis during development and adulthood. Human data relating altered TPH2 function to personality traits of negative emotionality and neurodevelopmental disorders characterized by deficits in cognitive control and emotion regulation are based on genetic association and are therefore not as robust as the experimental mouse results. Mouse models in conjunction with approaches focusing on TPH2 variants in humans provide unexpected views of 5-HT's role in brain development and in disorders related to negative emotionality, aggression and antisocial behaviour. PMID:22826343

  12. Bio-inspired synthesis of titania with polyamine induced morphology and phase transformation at room-temperature: insight into the role of the protonated amino group.

    PubMed

    Yan, Yong; Hao, Bo; Wang, Xiaobo; Chen, Ge

    2013-09-14

    Poly(allylamine hydrochloride) (PAAH), a mimic of biopolyamines, was used to induce the mineralization of titania at room-temperature, hollow spheres with a mixed phase (anatase and rutile) were obtained, and the fine anatase and rutile nanocrystals were observed mixing at the sub-10 nm scale on the hollow spheres. The structural information about the precipitated titania gained by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed a distinct dependence of the polymorph and morphology of the titania precipitates on the molecular structure of the polyamines and titanium precursors. Moreover, we have observed the phase transformation from anatase to rutile in the formation process of hollow spheres, and it was suggested that the protonated amino groups on PAAH played key roles in the transformation of both polymorphs and morphologies of titania. Additionally, poly(diallyldimethylammonium chloride) (PDDA), a long chain quaternary ammonium polymer, was used as another catalytic template for the synthesis of titania, which also led to a hollow structure with a mixture of anatase and TiO2-B.

  13. Diet micronutrient balance matters: How the ratio of dietary sterols/steroids affects development, growth and reproduction in two lepidopteran insects.

    PubMed

    Jing, Xiangfeng; Grebenok, Robert J; Behmer, Spencer T

    2014-08-01

    Insects lack the ability to synthesize sterols de novo so they acquire this essential nutrient from their food. Cholesterol is the dominant sterol found in most insects, but in plant vegetative tissue it makes up only a small fraction of the total sterol profile. Instead, plants mostly contain phytosterols; plant-feeding insects generate the majority of their cholesterol by metabolizing phytosterols. However, not all phytosterols are readily converted to cholesterol, and some are even deleterious when ingested above a threshold level. In a recent study we showed that caterpillars reared on tobacco accumulating novel sterols/steroids exhibited reduced performance, even when suitable sterols were present. In the current study we examined how the dominant sterols (cholesterol and stigmasterol) and steroids (cholestanol and cholestanone) typical of the modified tobacco plants affected two insect herbivores (Heliothis virescens and Helicoverpa zea). The sterols/steroids were incorporated into synthetic diets singly, as well as in various combinations, ratios and amounts. For each insect species, a range of performance values was recorded for two generations, with the eggs from the 1st-generation adults as the source of neonates for the 2nd-generation. Performance on the novel steroids (cholestanol and cholestanone) was extremely poor compared to suitable sterols (cholesterol and stigmasterol). Additionally, performance tended to decrease as the ratio of the novel dietary steroids increased. We discuss how the balance of different dietary sterols/steroids affected our two caterpillar species, relate this back to recent studies on sterol/steroid metabolism in these two species, and consider the potential application of sterol/steroid modification in crops.

  14. Sterols with antileishmanial activity isolated from the roots of Pentalinon andrieuxii

    PubMed Central

    Pan, Li; Lezama-Davila, Claudio M.; Isaac-Marquez, Angelica P.; Calomeni, Edward P.; Fuchs, James R.; Satoskar, Abhay R.; Kinghorn, A. Douglas

    2012-01-01

    A new cholesterol derivative, pentalinonsterol (cholest-4,20,24-trien-3-one, 1), and a new polyoxygenated pregnane sterol glycoside, pentalinonside (2), together with 18 known compounds, including 14 sterols (3–16), three coumarins (17–19), and a triterpene (20), were isolated from a n-hexane partition of a methanol extract of the roots of the Mexican medicinal plant Pentalinon andrieuxii. Structure elucidation of compounds 1 and 2 was accomplished by spectroscopic data interpretation. All isolates were evaluated in vitro for their antileishmanial activity. Among these compounds, 6,7-dihydroneridienone (15) was found to be the most potent principle against promastigotes of Leishmania mexicana (L. mexicana). The cholesterol analogue, pentalinonsterol (1), together with two known sterols, 24-methylcholest-4,24(28)-dien-3-one (3) and neridienone (16), also exhibited significant leishmanicidal activity in this same bioassay. Compounds 1, 3, 15, 16, cholest-4-en-3-one (4), and cholest-5,20,24-trien-3β-ol (7), showed strong antileishmanial activity against amastigotes of L. mexicana, and 4 was found to be the most potent agent with an IC50 value of 0.03 μM. All the isolates were also evaluated for their cytotoxicity in non-infected bone marrow-derived macrophages, but none of these compounds was found active towards this cell line. The intracellular parasites treated with compounds 1, 3, 4, 15, and 16 were further studied by electron microscopy; morphological abnormalities and destruction of the amastigotes were observed, as a result of treatment with these compounds. PMID:22840389

  15. Genetic Profiling of the Isoprenoid and Sterol Biosynthesis Pathway Genes of Trypanosoma cruzi

    PubMed Central

    Cosentino, Raúl O.; Agüero, Fernán

    2014-01-01

    In Trypanosoma cruzi the isoprenoid and sterol biosynthesis pathways are validated targets for chemotherapeutic intervention. In this work we present a study of the genetic diversity observed in genes from these pathways. Using a number of bioinformatic strategies, we first identified genes that were missing and/or were truncated in the T. cruzi genome. Based on this analysis we obtained the complete sequence of the ortholog of the yeast ERG26 gene and identified a non-orthologous homolog of the yeast ERG25 gene (sterol methyl oxidase, SMO), and we propose that the orthologs of ERG25 have been lost in trypanosomes (but not in Leishmanias). Next, starting from a set of 16 T. cruzi strains representative of all extant evolutionary lineages, we amplified and sequenced ∼24 Kbp from 22 genes, identifying a total of 975 SNPs or fixed differences, of which 28% represent non-synonymous changes. We observed genes with a density of substitutions ranging from those close to the average (∼2.5/100 bp) to some showing a high number of changes (11.4/100 bp, for the putative lathosterol oxidase gene). All the genes of the pathway are under apparent purifying selection, but genes coding for the sterol C14-demethylase, the HMG-CoA synthase, and the HMG-CoA reductase have the lowest density of missense SNPs in the panel. Other genes (TcPMK, TcSMO-like) have a relatively high density of non-synonymous SNPs (2.5 and 1.9 every 100 bp, respectively). However, none of the non-synonymous changes identified affect a catalytic or ligand binding site residue. A comparative analysis of the corresponding genes from African trypanosomes and Leishmania shows similar levels of apparent selection for each gene. This information will be essential for future drug development studies focused on this pathway. PMID:24828104

  16. Phytoestrogens and sterols in waters with cyanobacterial blooms - Analytical methods and estrogenic potencies.

    PubMed

    Procházková, Tereza; Sychrová, Eliška; Javůrková, Barbora; Večerková, Jaroslava; Kohoutek, Jiří; Lepšová-Skácelová, Olga; Bláha, Luděk; Hilscherová, Klára

    2017-03-01

    Compounds with estrogenic potencies and their adverse effects in surface waters have received much attention. Both anthropogenic and natural compounds contribute to overall estrogenic activity in freshwaters. Recently, estrogenic potencies were also found to be associated with cyanobacteria and their blooms in surface waters. The present study developed and compared the solid phase extraction and LC-MS/MS analytical approaches for determination of phytoestrogens (8 flavonoids - biochanin A, coumestrol, daidzein, equol, formononetin, genistein, naringenin, apigenin - and 5 sterols - ergosterol, β-sitosterol, stigmasterol, campesterol, brassicasterol) and cholesterol in water. The method was used for analyses of samples collected in stagnant water bodies dominated by different cyanobacterial species. Concentrations of individual flavonoids ranged from below the limit of detection to 3.58 ng/L. Sterols were present in higher amounts up to 2.25 μg/L. Biological potencies of these phytoestrogens in vitro were characterized using the hERα-HeLa-9903 cell line. The relative estrogenic potencies (compared to model estrogen - 17β-estradiol) of flavonoids ranged from 2.25E-05 to 1.26E-03 with coumestrol being the most potent. None of the sterols elicited estrogenic response in the used bioassay. Estrogenic activity was detected in collected field water samples (maximum effect corresponding to 2.07 ng/L of 17β-estradiol equivalents, transcriptional assay). At maximum phytoestrogens accounted for only 1.56 pg/L of 17β-estradiol equivalents, contributing maximally 8.5% of the total estrogenicity of the water samples. Other compounds therefore, most likely of anthropogenic origin such as steroid estrogens, are probably the major drivers of total estrogenic effects in these surface waters.

  17. Cost-benefit analysis of a plant sterol containing low-fat margarine for cholesterol reduction.

    PubMed

    Gerber, A; Evers, T; Haverkamp, H; Lauterbach, K W

    2006-12-01

    For decreasing the risk of coronary heart disease (CHD) it has been proposed to enrich food such as margarine with plant sterol esters which have been shown to reduce total and LDL cholesterol concentrations, two of the major risk factors. A Markov model was developed to assess the costs and benefits of consuming a low-fat plant sterol containing margarine (PS margarine). A health insurer's perspective was taken with a time frame of 10 years. Transition probabilities for CHD and CHD-related death were calculated on the basis of the Framingham risk equations. These were applied to a representative sample of the German population. The alteration in cholesterol levels after intake of PS margarine was estimated based on a meta-analysis of ten randomized controlled trials with parallel or crossover design that found a reduction of 5.7% in total cholesterol. Average annual costs of CHD were assumed to be at 3,000 euro. Costs for "no CHD" and "CHD-related death" were set to 0 euro since the intervention would solely be paid by the consumers. Sensitivity analyses were performed with regard to annual costs, risk estimation, PS margarine reduction in total cholesterol, discount factor, and risk of CHD-related death. The 10-year CHD risks are 6.1% (PS margarine) vs. 6.5% (control). Thus expected 10-year CHD costs are 696 euro (PS margarine) vs. 748 euro (control). The cost savings of 52 euro varied between 32 euro and 74 euro in the sensitivity analysis. A projection at the level of the population for which evidence (randomized controlled trials) exists that plant sterols lower cholesterol (25.35 million) leads to a reduction of 117,000 CHD cases over 10 years and a cost reduction of 1.3 billion euro for this time period (sensitivity analysis 0.8-1.9 billion euro).

  18. Titania binding peptides as templates in the biomimetic synthesis of stable titania nanosols: insight into the role of buffers in peptide-mediated mineralization.

    PubMed

    Puddu, Valeria; Slocik, Joseph M; Naik, Rajesh R; Perry, Carole C

    2013-07-30

    In this Article, we report the unusual behavior of two peptides (Ti-1 (QPYLFATDSLIK) and Ti-2 (GHTHYHAVRTQT)) with high affinity for titania that efficiently promote titania mineralization from an aqueous titanium bisammonium lactatodihydroxide (TiBALDH) solution, yielding small (ca. 4 nm) titania nanoparticles. As a result, we were able to produce for the first time using a biomimetic approach highly stable sub-10-nm titania sols. Both sequences show a high titania mineralization activity per unit peptide concentration and a capacity to control particle size and stabilize nanoparticles through specific surface interactions. We also show that phosphate ions disrupt the controlled particle formation and stabilization achieved in the presence of the two peptides. The products obtained from phosphate buffered solutions are titanium-containing materials (not pure oxide) with poor morphological control similar to those previously reported by others. Our results provide important insights into understanding the mechanism of titania mineralization in a range of different aqueous media (water, Tris, and phosphate buffer).

  19. Transcriptional integration of metabolism by the nuclear sterol-activated receptors LXR and FXR.

    PubMed

    Calkin, Anna C; Tontonoz, Peter

    2012-03-14

    Nuclear receptors are integrators of hormonal and nutritional signals, mediating changes to metabolic pathways within the body. Given that modulation of lipid and glucose metabolism has been linked to diseases including type 2 diabetes, obesity and atherosclerosis, a greater understanding of pathways that regulate metabolism in physiology and disease is crucial. The liver X receptors (LXRs) and the farnesoid X receptors (FXRs) are activated by oxysterols and bile acids, respectively. Mounting evidence indicates that these nuclear receptors have essential roles, not only in the regulation of cholesterol and bile acid metabolism but also in the integration of sterol, fatty acid and glucose metabolism.

  20. Transcriptional integration of metabolism by the nuclear sterol-activated receptors LXR and FXR

    PubMed Central

    2013-01-01

    Nuclear receptors are integrators of hormonal and nutritional signals, mediating changes to metabolic pathways within the body. Given that modulation of lipid and glucose metabolism has been linked to diseases including type 2 diabetes, obesity and atherosclerosis, a greater understanding of pathways that regulate metabolism in physiology and disease is crucial. The liver X receptors (LXRs) and the farnesoid X receptors (FXRs) are activated by oxysterols and bile acids, respectively. Mounting evidence indicates that these nuclear receptors have essential roles, not only in the regulation of cholesterol and bile acid metabolism but also in the integration of sterol, fatty acid and glucose metabolism. PMID:22414897

  1. Recombinant sterol esterase from Ophiostoma piceae: an improved biocatalyst expressed in Pichia pastoris

    PubMed Central

    2012-01-01

    Background The ascomycete Ophiostoma piceae produces a sterol esterase (OPE) with high affinity towards p-nitrophenol, glycerol and sterol esters. Its hydrolytic activity on natural mixtures of triglycerides and sterol esters has been proposed for pitch biocontrol in paper industry since these compounds produce important economic losses during paper pulp manufacture. Results Recently, this enzyme has been heterologously expressed in the methylotrophic yeast Pichia pastoris, and the hydrolytic activity of the recombinant protein (OPE*) studied. After the initial screening of different clones expressing the enzyme, only one was selected for showing the highest production rate. Different culture conditions were tested to improve the expression of the recombinant enzyme. Complex media were better than minimal media for production, but in any case the levels of enzymatic activity were higher (7-fold in the best case) than those obtained from O. piceae. The purified enzyme had a molecular mass of 76 kDa, higher than that reported for the native enzyme under SDS-PAGE (60 kDa). Steady-state kinetic characterization of the recombinant protein showed improved catalytic efficiency for this enzyme as compared to the native one, for all the assayed substrates (p-nitrophenol, glycerol, and cholesterol esters). Different causes for this were studied, as the increased glycosylation degree of the recombinant enzyme, their secondary structures or the oxidation of methionine residues. However, none of these could explain the improvements found in the recombinant protein. N-terminal sequencing of OPE* showed that two populations of this enzyme were expressed, having either 6 or 8 amino acid residues more than the native one. This fact affected the aggregation behaviour of the recombinant protein, as was corroborated by analytical ultracentrifugation, thus improving the catalytic efficiency of this enzyme. Conclusion P. pastoris resulted to be an optimum biofactory for the

  2. Click chemistry decoration of amino sterols as promising strategy to developed new leishmanicidal drugs.

    PubMed

    Porta, Exequiel O J; Carvalho, Paulo B; Avery, Mitchell A; Tekwani, Babu L; Labadie, Guillermo R

    2014-01-01

    A series of 1,2,3-triazolylsterols was prepared from pregnenolone through reductive amination and copper(I)-catalyzed azide-alkyne cycloaddition (click chemistry). The newly generated stereocenter of the key propargylamino intermediate provided a mixture of diastereomers which were separated chromatographically, and the configuration of the R isomer was determined by X-ray crystallography. Ten triazolyl sterols were prepared, and the products and intermediates were screened in vitro against different parasites, with some compounds presenting IC50 values in the low micromolar range against Leishmania donovani.

  3. Moving out: from sterol transport to drug resistance - the ABCG subfamily of efflux pumps.

    PubMed

    Moitra, Karobi; Silverton, Latoya; Limpert, Katy; Im, Kate; Dean, Michael

    2011-01-01

    The ATP binding cassette (ABC) proteins are typically ATP-driven transmembrane pumps that have been evolutionarily conserved from bacteria to humans. In humans these transporters are subdivided into seven subfamilies, ranging from A to G. The ABCG subfamily of transporters is the primary focus of this review. This subfamily of proteins has been conserved throughout evolution and plays a central role in several cellular processes, such as sterol homeostasis and multidrug resistance. Functional polymorphisms/mutations in some of these G-subfamily transporters have clinical consequences in humans.

  4. Synthesis, Biological Evaluation, and Molecular Modeling Studies of New Oxadiazole-Stilbene Hybrids against Phytopathogenic Fungi

    NASA Astrophysics Data System (ADS)

    Jian, Weilin; He, Daohang; Song, Shaoyun

    2016-08-01

    Natural stilbenes (especially resveratrol) play important roles in plant protection by acting as both constitutive and inducible defenses. However, their exogenous applications on crops as fungicidal agents are challenged by their oxidative degradation and limited availability. In this study, a new class of resveratrol-inspired oxadiazole-stilbene hybrids was synthesized via Wittig-Horner reaction. Bioassay results indicated that some of the compounds exhibited potent fungicidal activity against Botrytis cinerea in vitro. Among these stilbene hybrids, compounds 11 showed promising inhibitory activity with the EC50 value of 144.6 μg/mL, which was superior to that of resveratrol (315.6 μg/mL). Remarkably, the considerably abnormal mycelial morphology was observed in the presence of compound 11. The inhibitory profile was further proposed by homology modeling and molecular docking studies, which showed the possible interaction of resveratrol and oxadiazole-stilbene hybrids with the cytochrome P450-dependent sterol 14α-demethylase from B. cinerea (BcCYP51) for the first time. Taken together, these results would provide new insights into the fungicidal mechanism of stilbenes, as well as an important clue for biology-oriented synthesis of stilbene hybrids with improved bioactivity against plant pathogenic fungi in crop protection.

  5. Synthesis, Biological Evaluation, and Molecular Modeling Studies of New Oxadiazole-Stilbene Hybrids against Phytopathogenic Fungi

    PubMed Central

    Jian, Weilin; He, Daohang; Song, Shaoyun

    2016-01-01

    Natural stilbenes (especially resveratrol) play important roles in plant protection by acting as both constitutive and inducible defenses. However, their exogenous applications on crops as fungicidal agents are challenged by their oxidative degradation and limited availability. In this study, a new class of resveratrol-inspired oxadiazole-stilbene hybrids was synthesized via Wittig-Horner reaction. Bioassay results indicated that some of the compounds exhibited potent fungicidal activity against Botrytis cinerea in vitro. Among these stilbene hybrids, compounds 11 showed promising inhibitory activity with the EC50 value of 144.6 μg/mL, which was superior to that of resveratrol (315.6 μg/mL). Remarkably, the considerably abnormal mycelial morphology was observed in the presence of compound 11. The inhibitory profile was further proposed by homology modeling and molecular docking studies, which showed the possible interaction of resveratrol and oxadiazole-stilbene hybrids with the cytochrome P450-dependent sterol 14α-demethylase from B. cinerea (BcCYP51) for the first time. Taken together, these results would provide new insights into the fungicidal mechanism of stilbenes, as well as an important clue for biology-oriented synthesis of stilbene hybrids with improved bioactivity against plant pathogenic fungi in crop protection. PMID:27530962

  6. Rapid synthesis of hybrids and hollow PdO nanostructures by controlled in situ dissolution of a ZnO nanorod template: insights into the formation mechanism and thermal stability.

    PubMed

    Kundu, Subhajit; Ravishankar, N

    2016-01-21

    Hollow nanomaterials have attracted a lot of interest by virtue of their wide range of applications that arise primarily due to their unique architecture. A common strategy to synthesize hollow nanomaterials is by nucleation of the shell material over a preformed core and subsequent dissolution of the core in the second step. Herein an ultrafast, microwave route has been demonstrated, to synthesize PdO nanotubes in a single step using ZnO as a sacrificial template. The mechanism of the nanotube formation has been investigated in detail using control experiments. By tuning the starting ratio of PdCl2 : ZnO, hollow to hybrid PdO nanostructures could be obtained using the same method. Conversion of the PdO to Pd nanotubes has been shown by simple NaBH4 treatment. The thermal stability of the PdO nanotubes has been studied. The insights presented here are general and applicable for the synthesis of hybrids/hollow structures in other systems as well.

  7. Effects of bran on serum cholesterol, faecal mass, fat, bile acids and neutral sterols, and biliary lipids in patients with diverticular disease of the colon 1

    PubMed Central

    Tarpila, S.; Miettinen, T. A.; Metsäranta, L.

    1978-01-01

    Twenty-two patients with symptomatic diverticular disease of the colon were randomly allocated to control and high-fibre groups so that the long-term effect (up to 12 months) of bran on serum, faecal and biliary lipids could be studied. Even in cases of high initial values, faecal mass was increased by bran and the change was positively correlated with the change in dietary fibre. Faecal fat and dry weight were also increased. Faecal bile acids were initially slightly raised and were positively correlated with wet weight both off and on bran. The latter significantly decreased the excretion and concentration of bile acids, in particular the high initial values. The change in bile acids was not correlated with the change in dietary fibre or faecal wet weight. Sterol balance values indicated that the bran-induced decrease in faecal bile acids was associated with a lower cholesterol synthesis. Serum cholesterol decreased significantly in two hypercholesterolaemic individuals only. Correlations between different parameters revealed that the higher the initial level or the greater the drop in cholesterol synthesis, the greater the decrease in serum cholesterol. Bran had no effect on the biliary saturation of cholesterol. The percentage of biliary deoxycholate was negatively correlated with faecal mass (less so with faecal bile acid output) both before and during bran and was significantly decreased by bran. The percentage of cholic acid increased correspondingly and that of chenodeoxycholate remained unchanged. Faecal bile acids also indicated that the synthesis of the two primary bile acids was lowered by bran to the same degree. PMID:344156

  8. Cytoplasmic localization of sterol transcription factors Upc2p and Ecm22p in S.cerevisiae

    PubMed Central

    Marie, Chelsea; Leyde, Sarah; White, Theodore C

    2008-01-01

    Ergosterol homeostasis is a critical process for fungal cells. Paralogous zinc cluster transcription factors Upc2p and Ecm22p are major regulators of ergosterol biosynthesis in Saccharomyces cerevisiae. Upc2p and Ecm22p sense and respond to sterol depletion but their mechanism of activation has not been defined. Subcellular localization and functional expression of Upc2p–GFP and Ecm22p-GFP was monitored by fluorescence microscopy and flow cytometry in live yeast cells. Both fusion proteins localized to intracellular membranes and to perinuclear foci. Perinuclear localization of Upc2p-GFP and Ecm22p-GFP was increased when ergosterol biosynthesis was blocked by azole drug treatment. Nuclear localization in response to sterol depletion is consistent with the hypothesis that Upc2p and Ecm22p are trafficked from a membrane to the nucleus as a post-translational mechanism of sterol sensing. PMID:18675371

  9. Classification of vegetable oils according to their botanical origin using sterol profiles established by direct infusion mass spectrometry.

    PubMed

    Lerma-García, María J; Ramis-Ramos, Guillermo; Herrero-Martínez, José M; Simó-Alfonso, Ernesto F

    2008-04-01

    A simple and quick method to classify vegetable oils according to their botanical origin, based on direct infusion of sterol extracts into a mass spectrometer, was developed. Using mass spectrometry (MS) with either an electrospray ionization or an atmospheric pressure photoionization source, followed by linear discriminant analysis of the mass spectral data, oil samples corresponding to eight different botanical origins were perfectly classified with an excellent resolution among all the categories. An excellent correlation between the sterol profiles obtained by MS and by the official gas chromatography (with flame ionization detection) method was obtained. Thus, the proposed method is a promising alternative for sterol fingerprinting of vegetable oils, with the advantage that prior chromatographic separation is not required.

  10. Substrate Preferences and Catalytic Parameters Determined by Structural Characteristics of Sterol 14[alpha]-Demethylase (CYP51) from Leishmania infantum

    SciTech Connect

    Hargrove, Tatiana Y.; Wawrzak, Zdzislaw; Liu, Jialin; Nes, W. David; Waterman, Michael R.; Lepesheva, Galina I.

    2012-05-14

    Leishmaniasis is a major health problem that affects populations of {approx}90 countries worldwide, with no vaccine and only a few moderately effective drugs. Here we report the structure/function characterization of sterol 14{alpha}-demethylase (CYP51) from Leishmania infantum. The enzyme catalyzes removal of the 14{alpha}-methyl group from sterol precursors. The reaction is essential for membrane biogenesis and therefore has great potential to become a target for antileishmanial chemotherapy. Although L. infantum CYP51 prefers C4-monomethylated sterol substrates such as C4-norlanosterol and obtusifoliol (V{sub max} of {approx}10 and 8 min{sup -1}, respectively), it is also found to 14{alpha}-demethylate C4-dimethylated lanosterol (V{sub max} = 0.9 min{sup -1}) and C4-desmethylated 14{alpha}-methylzymosterol (V{sub max} = 1.9 min{sup -1}). Binding parameters with six sterols were tested, with K{sub d} values ranging from 0.25 to 1.4 {mu}m. Thus, L. infantum CYP51 is the first example of a plant-like sterol 14{alpha}-demethylase, where requirements toward the composition of the C4 atom substituents are not strict, indicative of possible branching in the postsqualene portion of sterol biosynthesis in the parasite. Comparative analysis of three CYP51 substrate binding cavities (Trypanosoma brucei, Trypanosoma cruzi, and L. infantum) suggests that substrate preferences of plant- and fungal-like protozoan CYP51s largely depend on the differences in the enzyme active site topology. These minor structural differences are also likely to underlie CYP51 catalytic rates and drug susceptibility and can be used to design potent and specific inhibitors.

  11. Potential of the Desert Locust Schistocerca gregaria (Orthoptera: Acrididae) as an Unconventional Source of Dietary and Therapeutic Sterols

    PubMed Central

    Cheseto, Xavier; Kuate, Serge Philibert; Tchouassi, David P.; Ndung’u, Mary; Teal, Peter E. A.; Torto, Baldwyn

    2015-01-01

    Insects are increasingly being recognized not only as a source of food to feed the ever growing world population but also as potential sources of new products and therapeutic agents, among which are sterols. In this study, we sought to profile sterols and their derivatives present in the desert locust, Schistocerca gregaria, focusing on those with potential importance as dietary and therapeutic components for humans. Using coupled gas chromatography-mass spectrometry (GC-MS), we analyzed and compared the quantities of sterols in the different sections of the gut and tissues of the locust. In the gut, we identified 34 sterols which showed a patchy distribution, but with the highest composition in the foregut (55%) followed by midgut (31%) and hindgut (14%). Fed ad libitum on wheat seedlings, five sterols unique to the insect were detected. These sterols were identified as 7-dehydrocholesterol, desmosterol, fucosterol, (3β, 5α) cholesta-8, 14, 24-trien-3-ol, 4, 4-dimethyl, and (3β, 20R) cholesta-5, 24-dien-3, 20-diol with the first three having known health benefits in humans. Incubation of the fore-, mid- and hindgut with cholesterol-[4-13C] yielded eight derivatives, three of these were detected in the gut of the desert locust after it had consumed the vegetative diet but were not detected in the diet. Our study shows that the desert locust ingests phytosterols from a vegetative diet and, amplifies and metabolizes them into derivatives with potential salutary benefits and we discuss our findings in this context. PMID:25970517

  12. Effects of plant stanol ester consumption on fasting plasma oxy(phyto)sterol concentrations as related to fecal microbiota characteristics.

    PubMed

    Baumgartner, Sabine; Mensink, Ronald P; Smet, Els De; Konings, Maurice; Fuentes, Susana; de Vos, Willem M; Plat, Jogchum

    2016-03-03

    Information regarding dietary effects on plasma oxyphytosterol concentrations as well as on the origin of oxyphytosterols is scarce. We hypothesized that plant sterols are oxidized in the intestinal lumen, mediated by microbial activity, followed by uptake into the circulation. To address this hypothesis, we carried out, a randomized, double blind, crossover study in 13 healthy subjects, who consumed for 3 weeks control and plant stanol ester enriched margarines (3.0g/d plant stanols) separated by a 4-week wash-out period. Plasma oxy(phyto)sterols were determined via GC-MS/MS, while microbiota analyses were performed on fecal DNA using a phylogenetic microarray to assess microbial composition and diversity. Plasma plant sterol concentrations did not correlate with plasma oxyphytosterols concentrations at baseline. Plant stanol consumption reduced serum sitosterol and campesterol concentrations (-37% and -38%), respectively (p<0.001), as well as plasma concentrations of 7β-OH-campesterol (-24%; p<0.05), 7β-OH-sitosterol (-17%; p<0.05) and 7-keto-sitosterol (-13%; p<0.05). Although the intestinal microbiota composition and diversity of the faecal contents were not different between the two periods, we observed significant correlations between several specific bacterial groups and plasma plant sterol, but not with plasma oxyphytosterol concentrations. In conclusion, plant stanol ester consumption reduced serum plant sterol and plasma oxyphytosterol concentrations, while intestinal microbiota composition and diversity were not changed. To definitely answer the effects of microbiota on oxyphytosterol formation, future studies could examine oxyphytosterol concentrations after changing intestinal microbial composition or by measuring intestinal oxyphytosterol formation after providing labelled non-oxidized plant sterols.

  13. Evolution of the Sterol Biosynthetic Pathway of Pythium insidiosum and Related Oomycetes Contributes to Antifungal Drug Resistance.

    PubMed

    Lerksuthirat, Tassanee; Sangcakul, Areeporn; Lohnoo, Tassanee; Yingyong, Wanta; Rujirawat, Thidarat; Krajaejun, Theerapong

    2017-04-01

    Pythiosis is a life-threatening infectious disease caused by the oomycete Pythium insidiosum Direct exposure to Py. insidiosum zoospores can initiate infections of the eye, limb, gastrointestinal tract, or skin/subcutaneous tissue. Treatments for pythiosis have mostly relied on surgery. Antifungal drugs are generally ineffective against Py. insidiosum However, one patient with an invasive Py. insidiosum infection recovered completely following treatment with terbinafine and itraconazole. Additionally, the drug target sterol biosynthetic enzymes have been identified in the oomycete Aphanomyces euteiches It remains an open question whether Py. insidiosum is susceptible to the antifungal drugs and harbors any of the known drug target enzymes. Here, we determined the in vitro susceptibilities of terbinafine and itraconazole against 30 isolates of Py. insidiosum We also analyzed endogenous sterols and searched for genes encoding the sterol biosynthetic enzymes in the genomes of Py. insidiosum and related oomycetes. The susceptibility assay showed that the growth of each of the Py. insidiosum isolates was inhibited by the antifungal agents, but only at difficult-to-achieve concentrations, which explains the clinical resistance of the drugs in the treatment of pythiosis patients. Genome searches of Py. insidiosum and related oomycetes demonstrated that these organisms contained an incomplete set of sterol biosynthetic enzymes. Gas chromatographic mass spectrometry did not detect any sterol end products in Py. insidiosum In conclusion, Py. insidiosum possesses an incomplete sterol biosynthetic pathway. Resistance to antifungal drugs targeting enzymes in the ergosterol biosynthetic pathway in Py. insidiosum was due to modifications or losses of some of the genes encoding the drug target enzymes.

  14. Intake of a Single Morning Dose of Standard and Novel Plant Sterol Preparations for 4 Weeks Does Not Dramatically Affect Plasma Lipid Concentrations in Humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recommendations for decreasing the risk of developing cardiovascular disease include increasing the intake of plant sterols and fish oil. The cholesterol-lowering action of plant sterols, when provided in a fish-oil fatty acids vehicle, remains to be investigated in humans. A randomized, crossover-f...

  15. Effect of Transition Metal Ions on the B Ring Oxidation of Sterols and their Kinetics in Oil-in-Water Emulsions

    NASA Astrophysics Data System (ADS)

    Lu, Baiyi; Hu, Yinzhou; Huang, Weisu; Wang, Mengmeng; Jiang, Yuan; Lou, Tiantian

    2016-06-01

    This study investigated the effect of metal ions on the oxidation of sterols and their kinetics in oil-in-water emulsions. Sterol substrates were added with different metal ions (Cu2+, Fe2+, Mn2+, Zn2+, Na+, and Mg2+) of five concentrations and investigated after 2 h of heating at 90 °C. The substrates added with Fe2+ and Cu2+ were heated continuously to evaluate the kinetics of four sterols and their corresponding sterol oxidation products (SOPs). Sterol oxidation increased as the metal ion concentration increased and the heating time was prolonged. The capability of the metal ions oxidizing sterols ranked as followed: Fe2+ > Cu2+ > Mn2+ > Zn2+ > Mg2+ ≈ Na+. 7-Ketosterol, 7β/7α-Hydroxysterol, 5β,6β/5α,6α-Epoxysterol, and Triols were the main oxides on the B ring, whereas 6β-Hydroxysterol was not or only slightly influenced. The acceleration of sterol degradation induced by Fe2+ and Cu2+, as well as the formation of oxidation products, followed first-order formation/elimination kinetics. The acceleration effect may be partly ascribed to the increase in elimination rate constant and formation rate constant. Transition metal ions can significantly induce sterol oxidation, which reduces food nutritional quality and triggers the formation of undesirable compounds, such as SOPs.

  16. Effect of Transition Metal Ions on the B Ring Oxidation of Sterols and their Kinetics in Oil-in-Water Emulsions

    PubMed Central

    Lu, Baiyi; Hu, Yinzhou; Huang, Weisu; Wang, Mengmeng; Jiang, Yuan; Lou, Tiantian

    2016-01-01

    This study investigated the effect of metal ions on the oxidation of sterols and their kinetics in oil-in-water emulsions. Sterol substrates were added with different metal ions (Cu2+, Fe2+, Mn2+, Zn2+, Na+, and Mg2+) of five concentrations and investigated after 2 h of heating at 90 °C. The substrates added with Fe2+ and Cu2+ were heated continuously to evaluate the kinetics of four sterols and their corresponding sterol oxidation products (SOPs). Sterol oxidation increased as the metal ion concentration increased and the heating time was prolonged. The capability of the metal ions oxidizing sterols ranked as followed: Fe2+ > Cu2+ > Mn2+ > Zn2+ > Mg2+ ≈ Na+. 7-Ketosterol, 7β/7α-Hydroxysterol, 5β,6β/5α,6α-Epoxysterol, and Triols were the main oxides on the B ring, whereas 6β-Hydroxysterol was not or only slightly influenced. The acceleration of sterol degradation induced by Fe2+ and Cu2+, as well as the formation of oxidation products, followed first-order formation/elimination kinetics. The acceleration effect may be partly ascribed to the increase in elimination rate constant and formation rate constant. Transition metal ions can significantly induce sterol oxidation, which reduces food nutritional quality and triggers the formation of undesirable compounds, such as SOPs. PMID:27328709

  17. Complete genome sequence of 'Mycobacterium neoaurum' NRRL B-3805, an androstenedione (AD) producer for industrial biotransformation of sterols.

    PubMed

    Rodríguez-García, Antonio; Fernández-Alegre, Estela; Morales, Alejandro; Sola-Landa, Alberto; Lorraine, Jess; Macdonald, Sandy; Dovbnya, Dmitry; Smith, Margaret C M; Donova, Marina; Barreiro, Carlos

    2016-04-20

    Microbial bioconversion of sterols into high value steroid precursors, such as 4-androstene-3,17-dione (AD), is an industrial challenge. Genes and enzymes involved in sterol degradation have been proposed, although the complete pathway is not yet known. The genome sequencing of the AD producer strain 'Mycobacterium neoaurum' NRRL B-3805 (formerly Mycobacterium sp. NRRL B-3805) will serve to elucidate the critical steps for industrial processes and will provide the basis for further genetic engineering. The genome comprises a circular chromosome (5 421 338bp), is devoid of plasmids and contains 4844 protein-coding genes.

  18. Sewage influence in a macrotidal estuary: Fatty acid and sterol distributions

    NASA Astrophysics Data System (ADS)

    Quemeneur, Michelle; Marty, Yanic

    1992-04-01

    Estuarine surface sediment and suspended matter from the Morlaix River estuary were analysed for fatty acids and sterols by HPLC and GC. This estuary represents a typical example of a coastal river estuary subjected to strong tides and receiving domestic wastes in its upper reaches. Wastewater fatty acid and sterol distribution patterns have been used to estimate the anthropogenic matter influx and its behaviour as an estuarine organic matter component. The 5 β-stanols, specific to fecal material and relatively persistent in the environment, provide a spatial view of sewage dispersion in estuarine waters and sediments and are used to calculate the relative importance of anthropogenic inputs in the degradable organic matter. Their distribution at high and low water indicates that anthropogenic particles are distributed throughout the estuary and may reach the coastal areas. However, owing to the dilution and the sedimentation processes, the anthropogenic matter contribution to the total organic matter is low in the outer estuary. By contrast, sediments from the upper estuary are strongly influenced by fresh anthropogenic inputs which may be detected by fatty acid fingerprint. The 18:1( n- 7)/18:1( n- 9) ratio which indicates the ability of the sediment to degrade the anthropogenic fresh material demonstrates a perturbation all along the narrow upper estuary.

  19. Endogenous sterol metabolites regulate growth of EGFR/KRAS-dependent tumors via LXR

    PubMed Central

    Gabitova, Linara; Restifo, Diana; Gorin, Andrey; Manocha, Kunal; Handorf, Elizabeth; Yang, Dong-Hua; Cai, Kathy Q.; Klein-Szanto, Andres J.; Cunningham, David; Kratz, Lisa E.; Herman, Gail E.; Golemis, Erica A.; Astsaturov, Igor

    2015-01-01

    Summary Meiosis activating sterols (MAS) are substrates of SC4MOL and NSDHL in the cholesterol pathway and are important for normal organismal development. Oncogenic transformation by EGFR or RAS increases the demand for cholesterol, suggesting a possibility for metabolic interference. To test this idea in vivo, we ablated Nsdhl in adult keratinocytes expressing KRASG12D. Strikingly, Nsdhl inactivation antagonized the growth of skin tumors, while having little effect on normal skin. Loss of Nsdhl induced the expression of ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, reduced the expression of low-density lipoprotein receptor (LDLR), decreased intracellular cholesterol and was dependent on the liver X receptor (LXR) α. Importantly, EGFR signaling opposed LXRα effects on cholesterol homeostasis, while an EGFR inhibitor synergized with LXRα agonists in killing cancer cells. Inhibition of SC4MOL or NSDHL, or activation of LXRα by sterol metabolites can be an effective strategy against carcinomas with activated EGFR-KRAS signaling. PMID:26344763

  20. Functional Analysis of Sterol Transporter Orthologues in the Filamentous Fungus Aspergillus nidulans

    PubMed Central

    Bühler, Nicole; Hagiwara, Daisuke

    2015-01-01

    Polarized growth in filamentous fungi needs a continuous supply of proteins and lipids to the growing hyphal tip. One of the important membrane compounds in fungi is ergosterol. At the apical plasma membrane ergosterol accumulations, which are called sterol-rich plasma membrane domains (SRDs). The exact roles and formation mechanism of the SRDs remained unclear, although the importance has been recognized for hyphal growth. Transport of ergosterol to hyphal tips is thought to be important for the organization of the SRDs. Oxysterol binding proteins, which are conserved from yeast to human, are involved in nonvesicular sterol transport. In Saccharomyces cerevisiae seven oxysterol-binding protein homologues (OSH1 to -7) play a role in ergosterol distribution between closely located membranes independent of vesicle transport. We found five homologous genes (oshA to oshE) in the filamentous fungi Aspergillus nidulans. The functions of OshA-E were characterized by gene deletion and subcellular localization. Each gene-deletion strain showed characteristic phenotypes and different sensitivities to ergosterol-associated drugs. Green fluorescent protein-tagged Osh proteins showed specific localization in the late Golgi compartments, puncta associated with the endoplasmic reticulum, or diffusely in the cytoplasm. The genes expression and regulation were investigated in a medically important species Aspergillus fumigatus, as well as A. nidulans. Our results suggest that each Osh protein plays a role in ergosterol distribution at distinct sites and contributes to proper fungal growth. PMID:26116213

  1. Brain sterol dys-regulation in sporadic AD and MCI: Relationship to heme oxygenase-1

    PubMed Central

    Hascalovici, Jacob R.; Vaya, Jacob; Khatib, Soliman; Holcroft, Christina A.; Zukor, Hillel; Song, Wei; Arvanitakis, Zoe; Bennett, David A.; Schipper, Hyman M.

    2009-01-01

    The objective of this study was to ascertain the impact of aging and Alzheimer disease (AD) on brain cholesterol (CH), CH precursors and oxysterol homeostasis. Altered CH metabolism and up-regulation of heme oxygenase-1 (HO-1) are characteristic of AD-affected neural tissues. We recently determined that HO-1 over-expression suppresses total CH levels by augmenting liver X receptor-mediated CH efflux and enhances oxysterol formation in cultured astroglia. Lipids and proteins were extracted from post-mortem human frontal cortex derived from subjects with sporadic AD, mild cognitive impairment (MCI) and no cognitive impairment (NCI; n=17 per group) enrolled in the Religious Orders Study, an ongoing clinical-pathologic study of aging and AD. ELISA was used to quantify human HO-1 protein expression from brain tissue and GC-MS to quantify total CH, CH precursors and relevant oxysterols. The relationships of sterol/oxysterol levels to HO-1 protein expression and clinical/demographic variables were determined by multivariable regression and non-parametric statistical analyses. Decreased CH, increased oxysterol and increased CH precursors concentrations in the cortex correlated significantly with HO-1 levels in MCI and AD, but not NCI. Specific oxysterols correlated with disease state, increasing neuropathological burden, neuropsychological impairment and age. A model featuring compensated and de-compensated states of altered sterol homeostasis in MCI and AD are presented based on the current data set and our earlier in vitro work. PMID:19522732

  2. Neutron diffraction studies of the interaction between amphotericin B and lipid-sterol model membranes

    NASA Astrophysics Data System (ADS)

    Foglia, Fabrizia; Lawrence, M. Jayne; Demeė, Bruno; Fragneto, Giovanna; Barlow, David

    2012-10-01

    Over the last 50 years or so, amphotericin has been widely employed in treating life-threatening systemic fungal infections. Its usefulness in the clinic, however, has always been circumscribed by its dose-limiting side-effects, and it is also now compromised by an increasing incidence of pathogen resistance. Combating these problems through development of new anti-fungal agents requires detailed knowledge of the drug's molecular mechanism, but unfortunately this is far from clear. Neutron diffraction studies of the drug's incorporation within lipid-sterol membranes have here been performed to shed light on this problem. The drug is shown to disturb the structures of both fungal and mammalian membranes, and co-localises with the membrane sterols in a manner consistent with trans-membrane pore formation. The differences seen in the membrane lipid ordering and in the distributions of the drug-ergosterol and drug-cholesterol complexes within the membranes are consistent with the drug's selectivity for fungal vs. human cells.

  3. A dietary test of putative deleterious sterols for the aphid Myzus persicae.

    PubMed

    Bouvaine, Sophie; Faure, Marie-Line; Grebenok, Robert J; Behmer, Spencer T; Douglas, Angela E

    2014-01-01

    The aphid Myzus persicae displays high mortality on tobacco plants bearing a transgene which results in the accumulation of the ketosteroids cholestan-3-one and cholest-4-en-3-one in the phloem sap. To test whether the ketosteroids are the basis of the plant resistance to the aphids, M. persicae were reared on chemically-defined diets with different steroid contents at 0.1-10 µg ml(-1). Relative to sterol-free diet and dietary supplements of the two ketosteroids and two phytosterols, dietary cholesterol significantly extended aphid lifespan and increased fecundity at one or more dietary concentrations tested. Median lifespan was 50% lower on the diet supplemented with cholest-4-en-3-one than on the cholesterol-supplemented diet. Aphid feeding rate did not vary significantly across the treatments, indicative of no anti-feedant effect of any sterol/steroid. Aphids reared on diets containing equal amounts of cholesterol and cholest-4-en-3-one showed fecundity equivalent to aphids on diets containing only cholesterol. Aphids were reared on diets that reproduced the relative steroid abundance in the phloem sap of the control and modified tobacco plants, and their performance on the two diet formulations was broadly equivalent. We conclude that, at the concentrations tested, plant ketosteroids support weaker aphid performance than cholesterol, but do not cause acute toxicity to the aphids. In plants, the ketosteroids may act synergistically with plant factors absent from artificial diets but are unlikely to be solely responsible for resistance of modified tobacco plants.

  4. Structure of Dehydroergosterol Monohydrate and Interaction with Sterol Carrier Protein-2

    PubMed Central

    McIntosh, Avery L.; Atshaves, Barbara P.; Gallegos, Adalberto M.; Storey, Stephen M.; Reibenspies, Joseph H.; Kier, Ann B.; Meyer, Edgar; Schroeder, Friedhelm

    2008-01-01

    Dehydroergosterol [ergosta-5,7,9(11),22-tetraen-3β-ol] is a naturally-occurring, fluorescent sterol utilized extensively to probe membrane cholesterol distribution, cholesterol-protein interactions, and intracellular cholesterol transport both in vitro and in vivo. In aqueous solutions, the low solubility of dehydroergosterol results in the formation of monohydrate crystals similar to cholesterol. Low temperature x-ray diffraction analysis reveals that dehydroergosterol monohydrate crystallizes in the space group P21 with 4 molecules in the unit cell and monoclinic crystal parameters a = 9.975(1)Å, b = 7.4731(9)Å, c = 34.054(4)Å, and β = 92.970(2)° somewhat similar to ergosterol monohydrate. The molecular arrangement is in a slightly closer packed bilayer structure resembling cholesterol monohydrate. Since dehydroergosterol fluorescence emission undergoes a quantum yield enhancement and red-shift of its maximum wavelength when crystallized, formation or disruption of microcrystals was monitored with high sensitivity using cuvette-based spectroscopy and multi-photon laser scanning imaging microscopy (MPLSM). This manuscript reports on the dynamical effect of sterol carrier protein-2 (SCP-2) interacting between aqueous dispersions of dehydroergosterol monohydrate microcrystal donors and acceptors consisting not only of model membranes but also vesicles derived from plasma membranes isolated by biochemical fractionation and affinity purification from Madin-Darby canine kidney cells. Furthermore, this study provides real-time measurements of the effect of increased SCP-2 levels on the rate of disappearance of dehydroergosterol microcrystals in living cells. PMID:19020914

  5. Proper Sterol Distribution Is Required for Candida albicans Hyphal Formation and Virulence

    PubMed Central

    McCourt, Paula; Liu, Hsing-Yin; Parker, Josie E.; Gallo-Ebert, Christina; Donigan, Melissa; Bata, Adam; Giordano, Caroline; Kelly, Steven L.; Nickels, Joseph T.

    2016-01-01

    Candida albicans is an opportunistic fungus responsible for the majority of systemic fungal infections. Multiple factors contribute to C. albicans pathogenicity. C. albicans strains lacking CaArv1 are avirulent. Arv1 has a conserved Arv1 homology domain (AHD) that has a zinc-binding domain containing two cysteine clusters. Here, we explored the role of the CaAHD and zinc-binding motif in CaArv1-dependent virulence. Overall, we found that the CaAHD was necessary but not sufficient for cells to be virulent, whereas the zinc-binding domain was essential, as Caarv1/Caarv1 cells expressing the full-length zinc-binding domain mutants, Caarv1C3S and Caarv1C28S, were avirulent. Phenotypically, we found a direct correlation between the avirulence of Caarv1/Caarv1, Caarrv1AHD, Caarv1C3S, and Caarv1C28S cells and defects in bud site selection, septa formation and localization, and hyphal formation and elongation. Importantly, all avirulent mutant strains lacked the ability to maintain proper sterol distribution. Overall, our results have established the importance of the AHD and zinc-binding domain in fungal invasion, and have correlated an avirulent phenotype with the inability to maintain proper sterol distribution. PMID:27587298

  6. Stability of sterols in phytosterol-enriched milk under different heating conditions.

    PubMed

    Menéndez-Carreño, María; Ansorena, Diana; Astiasarán, Iciar

    2008-11-12

    Commercially available phytosterol-enriched milk was subjected to usual and drastic heating conditions to evaluate the stability of the sterols at different treatments. Products showed 422.2 mg of phytosterols/100 g of milk and 132 microg of sterol oxidation products (SOPs)/g of fat (277 microg of SOPs/100 g of milk). Schaal oven conditions (24 h/65 degrees C, equivalent to 1 month of storage at room temperature) reduced the phytosterol content by only 4%. Drastic heating treatments (2 min of microwave heating at 900 W or 15 min of electrical heating at 90 degrees C) led to a 60% decrease of total phytosterol content, with a significant increase of TBARs. The oxysterol amount under those conditions (which was higher in microwave-treated samples) was lower than expected, probably because of the degradation of the oxidation products. Usual heating conditions (1.5 min of microwaves) maintained phytosterol content on physiologically active values (301 mg/100 g of milk) with oxidation percentages around 0.12-0.40% for phytosterols and 1.13% for cholesterol.

  7. Antioxidant and Anti-Osteoporotic Activities of Aromatic Compounds and Sterols from Hericium erinaceum.

    PubMed

    Li, Wei; Lee, Sang Hyun; Jang, Hae Dong; Ma, Jin Yeul; Kim, Young Ho

    2017-01-11

    Hericium erinaceum, commonly called lion's mane mushroom, is a traditional edible mushroom widely used in culinary applications and herbal medicines in East Asian countries. In this study, a new sterol, cerevisterol 6-cinnamate (6), was isolated from the fruiting bodies of H. erinaceum together with five aromatic compounds 1-5 and five sterols 7-11. The chemical structures of these compounds were elucidated using chemical and physical methods and comparison of HRESIMS, ¹D-NMR (¹H, (13)C, and DEPT) and 2D-NMR (COSY, HMQC, HMBC, and NOESY) spectra with previously reported data. The antioxidant and anti-osteoporotic activities of extracts and the isolated compounds 1-11 were investigated. All compounds exhibited peroxyl radical-scavenging capacity but only compounds 1, 3, and 4 showed potent reducing capacity. Moreover, compounds 1, 2, 4, and 5 showed moderate effects on cellular antioxidant activity and inhibited the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclastic differentiation. These results suggested that H. erinaceum could be utilized in the development of natural antioxidant and anti-osteoporotic nutraceuticals and functional foods.

  8. Sterols from Mytilidae show anti-aging and neuroprotective effects via anti-oxidative activity.

    PubMed

    Sun, Yujuan; Lin, Yanfei; Cao, Xueli; Xiang, Lan; Qi, Jianhua

    2014-11-25

    For screening anti-aging samples from marine natural products, K6001 yeast strain was employed as a bioassay system. The active mussel extract was separated to give an active sterol fraction (SF). SF was further purified, and four sterol compounds were obtained. Their structures were determined to be cholesterol (CHOL), brassicasterol, crinosterol, and 24-methylenecholesterol. All compounds showed similar anti-aging activity. To understand the action mechanism involved, anti-oxidative experiments, reactive oxygen species (ROS) assays, and malondialdehyde (MDA) tests were performed on the most abundant compound, CHOL. Results indicated that treatment with CHOL increases the survival rate of yeast under oxidative stress and decreases ROS and MDA levels. In addition, mutations of uth1, skn7, sod1, and sod2, which feature a K6001 background, were employed and the lifespans of the mutations were not affected by CHOL. These results demonstrate that CHOL exerts anti-aging effects via anti-oxidative stress. Based on the connection between neuroprotection and anti-aging, neuroprotective experiments were performed in PC12 cells. Paraquat was used to induce oxidative stress and the results showed that the CHOL and SF protect the PC12 cells from the injury induced by paraquat. In addition, these substance exhibited nerve growth factor (NGF) mimic activities again confirmed their neuroprotective function.

  9. Detection of non-sterol isoprenoids by HPLC-MS/MS

    PubMed Central

    Henneman, Linda; van Cruchten, Arno G.; Denis, Simone W.; Amolins, Michael W.; Placzek, Andrew T.; Gibbs, Richard A.; Kulik, Willem; Waterham, Hans R.

    2012-01-01

    Isoprenoids constitute an important class of biomolecules that participate in many different cellular processes. Most available detection methods only allow the identification of one or two specific non-sterol isoprenoid intermediates following radioactive or fluorescent labeling. We here report a rapid, non-radioactive and sensitive procedure for the simultaneous detection and quantification of the 8 main non-sterol intermediates of the isoprenoid biosynthesis pathway by means of tandem mass spectrometry. Intermediates were analyzed by HPLC-MS/MS in the multiple reaction monitoring mode using a silica-based C18 HPLC column. For quantification, their stable-isotope-labeled analogues were used as internal standards. HepG2 cells were used to validate the method. Mevalonate, phosphomevalonate and the 6 subsequent isoprenoid-pyrophosphates were readily determined with detection limits ranging from 0.03 to 1.0 μmol/L. The intra- and interassay variations for HepG2 cell homogenates supplemented with isoprenoid intermediates were 3.6–10.9% and 4.4–11.9%, respectively. Under normal culturing conditions, isoprenoid intermediates in HepG2 cells were below detection limits. However, incubation of the cells with pamidronate, an inhibitor of farnesyl pyrophosphate synthase, resulted in increased levels of MVA, IPP/DMAPP and GPP. This method will be suitable to measure profiles of isoprenoid intermediates in cells with compromised isoprenoid biosynthesis, and to determine the specificity of potential inhibitors of the pathway. PMID:18782552

  10. Common sources and estimated intake of plant sterols in the Spanish diet.

    PubMed

    Jiménez-Escrig, Antonio; Santos-Hidalgo, Ana B; Saura-Calixto, Fulgencio

    2006-05-03

    Plant sterols (PS) are minor lipid components of plants, which may have potential health benefits, mainly based in their cholesterol-lowering effect. The aim of this study was to determine the composition and content of PS in plant-based foods commonly consumed in Spain and to estimate the PS intake in the Spanish diet. For this purpose, the determination of PS content, using a modern methodology to measure free, esterified, and glycosidic sterol forms, was done. Second, an estimation of the intake of PS, using the Spanish National Food Consumption data, was made. The daily intake per person of PS--campesterol, beta-sitosterol, stigmasterol, and stigmastanol--in the Spanish diet was estimated at 276 mg, the largest component being beta-sitosterol (79.7%). Other unknown compounds, tentatively identified as PS, may constitute a considerable potential intake (99 mg). When the daily PS intake among European diets was compared in terms of campesterol, beta-sitosterol, stigmasterol, and stigmastanol, the PS intake in the Spanish diet was in the same range of other countries such as Finland (15.7% higher) or The Netherlands (equal). However, some qualitative differences in the PS sources were detected, that is, the predominant brown bread and vegetable fat consumption in the northern diets versus the white bread and vegetable oil consumption in the Spanish diet. These differences may help to provide a link between the consumption of PS and healthy effects of the diet.

  11. Desmosterol, the main sterol in rabbit semen: distribution among semen subfractions and its role in the in vitro spermatozoa acrosome reaction and motility

    PubMed Central

    Mourvaki, Evangelia; Cardinali, Raffaella; Roberti, Rita; Dal Bosco, Alessandro; Castellini, Cesare

    2010-01-01

    Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form (94.3%), were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol (58.5% of total sterols) and cholesterol (35.9% of total sterols). Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% (in the prostatic secretory granules, PSGs) to 63.8% (in the seminal plasma). Spermatozoa contained an intermediate proportion of desmosterol (59.8%), which was asymmetrically distributed between the heads (52.0% of the total content of sterols) and the tails (81.8%). Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L−1. In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation. PMID:20729867

  12. Neuronal Activity-Induced Sterol Regulatory Element Binding Protein-1 (SREBP1) is Disrupted in Dysbindin-Null Mice-Potential Link to Cognitive Impairment in Schizophrenia.

    PubMed

    Chen, Yong; Bang, Sookhee; McMullen, Mary F; Kazi, Hala; Talbot, Konrad; Ho, Mei-Xuan; Carlson, Greg; Arnold, Steven E; Ong, Wei-Yi; Kim, Sangwon F

    2017-04-01

    Schizophrenia is a chronic debilitating neuropsychiatric disorder that affects about 1 % of the population. Dystrobrevin-binding protein 1 (DTNBP1 or dysbindin) is one of the Research Domain Constructs (RDoC) associated with cognition and is significantly reduced in the brain of schizophrenia patients. To further understand the molecular underpinnings of pathogenesis of schizophrenia, we have performed microarray analyses of the hippocampi from dysbindin knockout mice, and found that genes involved in the lipogenic pathway are suppressed. Moreover, we discovered that maturation of a master transcriptional regulator for lipid synthesis, sterol regulatory element binding protein-1 (SREBP1) is induced by neuronal activity, and is required for induction of the immediate early gene ARC (activity-regulated cytoskeleton-associated protein), necessary for synaptic plasticity and memory. We found that nuclear SREBP1 is dramatically reduced in dysbindin-1 knockout mice and postmortem brain tissues from human patients with schizophrenia. Furthermore, activity-dependent maturation of SREBP1 as well as ARC expression were attenuated in dysbindin-1 knockout mice, and these deficits were restored by an atypical antipsychotic drug, clozapine. Together, results indicate an important role of dysbindin-1 in neuronal activity induced SREBP1 and ARC, which could be related to cognitive deficits in schizophrenia.

  13. Trichodiene Production in a Trichoderma harzianum erg1-Silenced Strain Provides Evidence of the Importance of the Sterol Biosynthetic Pathway in Inducing Plant Defense-Related Gene Expression.

    PubMed

    Malmierca, M G; McCormick, S P; Cardoza, R E; Monte, E; Alexander, N J; Gutiérrez, S

    2015-11-01

    Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both the antagonistic fungus and the plant. The terpene trichodiene (TD) elicits the expression of genes related to tomato defense and to Botrytis virulence. We show here that TD itself is able to induce the expression of Botrytis genes involved in the synthesis of botrydial (BOT) and also induces terpene gene expression in Trichoderma spp. The terpene ergosterol, in addition to its role as a structural component of the fungal cell membranes, acts as an elicitor of defense response in plants. In the present work, using a transformant of T. harzianum, which is silenced in the erg1 gene and accumulates high levels of squalene, we show that this ergosterol precursor also acts as an important elicitor molecule of tomato defense-related genes and induces Botrytis genes involved in BOT biosynthesis, in both cases, in a concentration-dependent manner. Our data emphasize the importance of a balance of squalene and ergosterol in fungal interactions as well as in the biocontrol activity of Trichoderma spp.

  14. Vitamin D and sterol composition of ten types of mushrooms from retail suppliers in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vitamin D, ergosterol, ergosterol metabolites, and phytosterols were analyzed in ten mushroom types sampled nationwide in the U.S. to update the USDA Nutrient Database for Standard Reference. Sterols were analyzed by GC-FID with mass spectrometric confirmation of components. Vitamin D was assayed ...

  15. Use of Enterococcus, BST and sterols as indicators for poultry pollution source tracking in surface and groundwater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study has applied Enterococcus, Bacterial Source Tracking (BST) and sterol analysis for pollution source identification from poultry sources. Fecal contamination was detected in 100% of surface water and 15% of groundwater sites tested. E. faecium was the dominant species in aged litter sampl...

  16. BIOCHEMISTRY OF DINOFLAGELLATE LIPIDS, WITH PARTICULAR REFERENCE TO THE FATTY ACID AND STEROL COMPOSITION OF A KARENIA BREVIS BLOOM

    EPA Science Inventory

    Leblond, Jeffrey D., Terence J. Evens and Peter J. Chapman. 2003. Biochemistry of Dinoflagellate Lipids, with Particular Reference to the Fatty Acid and Sterol Composition of a Karenia brevis Bloom. Phycologia. 42(4):324-331. (ERL,GB 1160).

    The harmful marine dinoflagella...

  17. Lamellar self-assemblies of single-chain amphiphiles and sterols and their derived liposomes: distinct compositions and distinct properties.

    PubMed

    Cui, Zhong-Kai; Lafleur, Michel

    2014-02-01

    Typically, single-chain amphiphiles and sterols do not form fluid lamellar phases once hydrated individually. Most of the single-chain amphiphiles form actually micelles in aqueous environments, while sterols display a very limited solubility in water. However, under certain conditions, mixtures of single-chain amphiphiles and sterols lead to the formation of stable fluid bilayers. Over the past decade, several of these systems leading to fluid lamellar self-assemblies have been identified and this article reviews the current knowledge relative to these non-phospholipid bilayers made of single-chain amphiphiles and sterols. It presents an integrated view about the molecular features that are required for their stability, the properties they share, and the origin of these characteristics. It was also shown that these lamellar systems could lead to the formation of unilamellar vesicles, similar to phospholipid based liposomes. These vesicles display distinct properties that make them potentially appealing for technological applications; they display a limited permeability, they are stable, they are formed with molecules that are relatively chemically inert (and relatively cheap), and they can be readily functionalized. The features of these distinct liposomes and their technological applications are reviewed. Finally, the putative biological implications of these non-phospholipid fluid bilayers are also discussed.

  18. Pigmented Rice Bran and Plant Sterol Combination Reduces Serum Lipids in Overweight and Obese Adults

    PubMed Central

    Hongu, Nobuko; Kitts, David D.; Zawistowski, Jerzy; Dossett, Cynthia M.; Kopeć, Aneta; Pope, Benjamin T.; Buchowski, Maciej S.

    2015-01-01

    Objective This study investigated the dietary effect of including pigmented rice bran with or without plant sterols on lipid profiles during energy restriction–induced weight loss in overweight and obese adults not taking cholesterol-lowering medication. In addition, the study examined the effect of intervention on biomarkers of oxidative stress and inflammation. Methods A group of 24 overweight and obese adults (age: 43 ± 6 years, body mass index 32 ± 1 kg/m2, 18 females) were randomized to a 25% calorie-restricted diet containing either pigmented rice bran (RB) or the RB with addition of plant sterols (RB + PS) snack bars for 8 weeks. The individualized nutrient-balanced diet contained ~70% of daily energy needs assessed from indirect calorimetry measured resting energy expenditure (EE) and physical activity-related EE assessed using accelerometry. Anthropometrics, blood pressure, blood lipids, glucose, urinary F2-isoprostanes, C-reactive protein, insulin, and leptin were measured at baseline and after 8 weeks of intervention. Results Participants lost approximately 4.7 ± 2.2 kg (p < 0.001). Weight loss was not significant between the RB + PS and RB group (p = 0.056). Changes in body fat corresponded to changes in body weight. Average decrease in total cholesterol was significantly higher in the RB + PS group than in the RB group (difference 36 ± 25 g/dL vs 7 ± 16 g/dL; p = 0.044). A similar pattern was observed for the decrease in low-density lipoprotein (LDL) cholesterol (difference 22.3 ± 25.2 g/dL vs 4.4 ± 18.9 g/dL; p = 0.062). Changes in systolic blood pressure, serum levels of leptin, and F2-isoprostanes were significant between baseline values and after 8 weeks on the diet in both groups (p < 0.05) but did not differ between the 2 groups. Conclusions A nutrient-balanced and energy-restricted diet supplemented with rice bran and plant sterols resulted in a significant decrease in total and LDL cholesterol in overweight and obese adults. PMID

  19. Sterol-inhibiting fungicide impacts on soil microbial ecology in Atlantic Coastal Plain soils

    NASA Astrophysics Data System (ADS)

    White, P. M.; Potter, T. L.; Strickland, T. C.

    2008-12-01

    Seventy-five percent of the peanuts (Arachus hypogaia) produced in the United States are grown in the Atlantic Coastal Plain region. Portions of this area, including Alabama and Georgia, exhibit a subtropical climate that promotes soil-borne plant fungal diseases. Most fields receive repeated fungicide applications during the growing season to suppress the disease causing organisms, such as Sclerotium rolfsii, Rhizoctonia solani, and Cylindrocladium parasiticum. Information regarding fungicide effects on the soil microbial community, with components principally responsible for transformation and fate of fungicides and other soil-applied pesticides, is limited. The objectives of the study were to assess soil microbial community response to (1) varying rates of the sterol-inhibiting fungicide tebuconazole (0, single application, season max, 2x season max), and (2) field rates of the sterol-inhibitors cyproconazole, prothioconazole, tebuconazole, and flutriafol, and thiol-competitor chlorothalonil. The sterol-inhibitors exhibited different half lives, as listed in the FOOTPRINT database, ranging from <1 day to >1300 d. Chlorothalonil was chosen because it is the most frequently applied fungicide to peanut. Shifts in the fungi, gram positive and gram negative bacteria, were monitored during the experiments using phospholipid fatty acid (PLFA) profiles. Ergosterol levels and pesticide decay rates were also monitored to evaluate the effectiveness of the fungicide and soil residence time, respectively. In the rate study, the highest rate of tebuconazole reduced the fungal biomarker 18:2ω6,9c to 2.6 nmol g-1 dry soil at 17 d, as compared to the control (4.1 nmol g-1 dry soil). However, levels of the fungal PLFA biomarker were similar regardless of rate at 0 and 32 d. The gram negative bacterial PLFA mole percent was greater at 17 d for the two highest rates of tebuconazole, but was similar at 0 and 32 d. Gram positive and fungal mole percents were not affected at any time

  20. The lipid lowering effect of plant sterol ester capsules in hypercholesterolemic subjects

    PubMed Central

    Acuff, Robert V; Cai, David J; Dong, Zhi-Ping; Bell, Doris

    2007-01-01

    Background Foods enriched with phytosterols have been proven to be an effective therapy to improve blood lipid profiles. However, none of the studies have investigated the efficacy in lipid lowering of plant sterol esters (PSE) in capsule form. The objective of this study is to determine if the plant sterol esters (PSE) in capsule form (1.3 grams of PSE/day) lowered plasma cholesterol levels and lipid ratios in free-living hypercholesterolemic subjects during a 4-week intervention period. Methods Sixteen subjects participated in a double-blind, placebo-controlled, sequential study with a 4-week placebo phase followed by a 2-week wash-out period and a 4-week treatment phase. Subjects were instructed to maintain stable diet pattern and physical activities. Blood samples were collected at 7, 21 and 28 days of each phase. The primary measurements were change in plasma total cholesterol (TC), HDL-cholesterol (HDL) and LDL-cholesterol (LDL) between phases and within each phase. The secondary measurements were change in triglycerides, lipoprotein ratios (TC/HDL, LDL/HDL) and C-reactive protein (CRP). Results In comparison to placebo, LDL-cholesterol was significantly reduced by 7% and 4% (P < 0.05) at both week 3 and week 4; HDL at week 3 of the treatment was significantly increased by 9% (P < 0.01), but not at week 4 (4%); total cholesterol was not significantly different from placebo throughout the period, TC/HDL and LDL/HDL were significantly reduced by (8%, 8%, 6%, 10%, respectively) (P < 0.01) at both week 3 and week 4. CRP and triglycerides did not differ either between the two phases or during the treatment phase. Conclusion In conclusion, plant sterol ester capsule is effective in improving lipid profiles among hypercholesterolemic subjects in a free-living setting at the minimum dosage recommended by FDA. The significant improved lipid profiles were reached after three weeks of administration. To achieve better lipid lowering results, higher dosages and

  1. Docosahexaenoic acid inhibits proteolytic processing of sterol regulatory element-binding protein-1c (SREBP-1c) via activation of AMP-activated kinase.

    PubMed

    Deng, Xiong; Dong, Qingming; Bridges, Dave; Raghow, Rajendra; Park, Edwards A; Elam, Marshall B

    2015-12-01

    In hyperinsulinemic states including obesity and T2DM, overproduction of fatty acid and triglyceride contributes to steatosis of the liver, hyperlipidemia and hepatic insulin resistance. This effect is mediated in part by the transcriptional regulator sterol responsive element binding protein-1c (SREBP-1c), which stimulates the expression of genes involved in hepatic fatty acid and triglyceride synthesis. SREBP-1c is up regulated by insulin both via increased transcription of nascent full-length SREBP-1c and by enhanced proteolytic processing of the endoplasmic reticulum (ER)-bound precursor to yield the transcriptionally active n-terminal form, nSREBP-1c. Polyunsaturated fatty acids of marine origin (n-3 PUFA) prevent induction of SREBP-1c by insulin thereby reducing plasma and hepatic triglycerides. Despite widespread use of n-3 PUFA supplements to reduce triglycerides in clinical practice, the exact mechanisms underlying their hypotriglyceridemic effect remain elusive. Here we demonstrate that the n-3 PUFA docosahexaenoic acid (DHA; 22:5 n-3) reduces nSREBP-1c by inhibiting regulated intramembrane proteolysis (RIP) of the nascent SREBP-1c. We further show that this effect of DHA is mediated both via activation of AMP-activated protein kinase (AMPK) and by inhibition of mechanistic target of rapamycin complex 1 (mTORC1). The inhibitory effect of AMPK on SREBP-1c processing is linked to phosphorylation of serine 365 of SREBP-1c in the rat. We have defined a novel regulatory mechanism by which n-3 PUFA inhibit induction of SREBP-1c by insulin. These findings identify AMPK as an important negative regulator of hepatic lipid synthesis and as a potential therapeutic target for hyperlipidemia in obesity and T2DM.

  2. Differential hepatocellular zonation pattern of cholesterol 7alpha-hydroxylase (Cyp7a1) and sterol 12alpha-hydroxylase (Cyp8b1) in the mouse.

    PubMed

    Wang, Jin; Olin, Maria; Rozell, Björn; Björkhem, Ingemar; Einarsson, Curt; Eggertsen, Gösta; Gåfvels, Mats

    2007-03-01

    The synthesis of primary bile acids is confined to the hepatocytes. This study aimed to evaluate the expression pattern within the liver architecture of the rate-limiting enzyme of the neutral pathway, cholesterol 7alpha-hydroxylase (Cyp7a1), and sterol 12alpha-hydroxylase (Cyp8b1), the enzyme necessary for the synthesis of cholic acid. Specific Cyp8b1 and Cyp7a1 peptide antiserums were used for immunohistochemical staining of livers from wild type and Cyp8b1 null mice, the latter instead expressing beta-galactosidase (beta-Gal) as a replacement reporter gene. Cyp8b1 was mainly expressed in the hepatocytes in a zonal pattern surrounding the central vein while the areas surrounding the portal zones showed much lower levels. The zonation was maintained in cholic acid-depleted mice using beta-Gal as a reporter protein. Cyp7a1 expression in wild type mice also showed a zonal distribution pattern, although less distinct, with a maximal expression within a 1-2 cell thick layer of hepatocytes surrounding the central vein. In Cyp8b1 null mice, a more intense staining was obtained, in accordance with the higher expression level of Cyp7a1, although the overall expression pattern was maintained. Our results in mice indicate possible differences in the regulation of the cellular zonation of Cyp7a1 and Cyp8b1. Also, cholic acid affects the set-point of Cyp7a1 expression but not its zonal distribution.

  3. Tlr4-mutant mice are resistant to acute alcohol-induced sterol-regulatory element binding protein activation and hepatic lipid accumulation.

    PubMed

    Zhang, Zhi-Hui; Liu, Xiao-Qian; Zhang, Cheng; He, Wei; Wang, Hua; Chen, Yuan-Hua; Liu, Xiao-Jing; Chen, Xi; Xu, De-Xiang

    2016-09-15

    Previous studies demonstrated that acute alcohol intoxication caused hepatic lipid accumulation. The present study showed that acute alcohol intoxication caused hepatic lipid accumulation in Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic sterol-regulatory element binding protein (SREBP)-1, a transcription factor regulating fatty acid and triglyceride (TG) synthesis, was activated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic Fas, Acc, Scd-1 and Dgat-2, the key genes for fatty acid and TG synthesis, were up-regulated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Additional experiment showed that hepatic MyD88 was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic NF-κB was activated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Moreover, hepatic GSH content was reduced and hepatic MDA level was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic CYP2E1 was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic p67phox and gp91phox, two NADPH oxidase subunits, were up-regulated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Alpha-phenyl-N-t-butylnitrone (PBN), a free radical spin-trapping agent, protected against alcohol-induced hepatic SREBP-1 activation and hepatic lipid accumulation. In conclusion, Tlr4-mutant mice are resistant to acute alcohol-induced hepatic SREBP-1 activation and hepatic lipid accumulation.

  4. Tlr4-mutant mice are resistant to acute alcohol-induced sterol-regulatory element binding protein activation and hepatic lipid accumulation

    PubMed Central

    Zhang, Zhi-Hui; Liu, Xiao-Qian; Zhang, Cheng; He, Wei; Wang, Hua; Chen, Yuan-Hua; Liu, Xiao-Jing; Chen, Xi; Xu, De-Xiang

    2016-01-01

    Previous studies demonstrated that acute alcohol intoxication caused hepatic lipid accumulation. The present study showed that acute alcohol intoxication caused hepatic lipid accumulation in Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic sterol-regulatory element binding protein (SREBP)-1, a transcription factor regulating fatty acid and triglyceride (TG) synthesis, was activated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic Fas, Acc, Scd-1 and Dgat-2, the key genes for fatty acid and TG synthesis, were up-regulated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Additional experiment showed that hepatic MyD88 was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic NF-κB was activated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Moreover, hepatic GSH content was reduced and hepatic MDA level was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic CYP2E1 was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic p67phox and gp91phox, two NADPH oxidase subunits, were up-regulated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Alpha-phenyl-N-t-butylnitrone (PBN), a free radical spin-trapping agent, protected against alcohol-induced hepatic SREBP-1 activation and hepatic lipid accumulation. In conclusion, Tlr4-mutant mice are resistant to acute alcohol-induced hepatic SREBP-1 activation and hepatic lipid accumulation. PMID:27627966

  5. Honokiol reverses alcoholic fatty liver by inhibiting the maturation of sterol regulatory element binding protein-1c and the expression of its downstream lipogenesis genes

    SciTech Connect

    Yin Huquan; Kim, Youn-Chul; Chung, Young-Suk; Kim, Young-Chul; Shin, Young-Kee; Lee, Byung-Hoon

    2009-04-01

    Ethanol induces hepatic steatosis via a complex mechanism that is not well understood. Among the variety of molecules that have been proposed to participate in this mechanism, the sterol regulatory element (SRE)-binding proteins (SREBPs) have been identified as attractive targets for therapeutic intervention. In the present study, we evaluated the effects of honokiol on alcoholic steatosis and investigated its possible effect on the inhibition of SREBP-1c maturation. In in vitro studies, H4IIEC3 rat hepatoma cells developed increased lipid droplets when exposed to ethanol, but co-treatment with honokiol reversed this effect. Honokiol inhibited the maturation of SREBP-1c and its translocation to the nucleus, the binding of nSREBP-1c to SRE or SRE-related sequences of its lipogenic target genes, and the expression of genes for fatty acid synthesis. In contrast, magnolol, a structural isomer of honokiol, had no effect on nSREBP-1c levels. Male Wistar rats fed with a standard Lieber-DeCarli ethanol diet for 4 weeks exhibited increased hepatic triglyceride and decreased hepatic glutathione levels, with concomitantly increased serum alanine aminotransferase and TNF-{alpha} levels. Daily administration of honokiol (10 mg/kg body weight) by gavage during the final 2 weeks of ethanol treatment completely reversed these effects on hepatotoxicity markers, including hepatic triglyceride, hepatic glutathione, and serum TNF-{alpha}, with efficacious abrogation of fat accumulation in the liver. Inhibition of SREBP-1c protein maturation and of the expression of Srebf1c and its target genes for hepatic lipogenesis were also observed in vivo. A chromatin immunoprecipitation assay demonstrated inhibition of specific binding of SREBP-1c to the Fas promoter by honokiol in vivo. These results demonstrate that honokiol has the potential to ameliorate alcoholic steatosis by blocking fatty acid synthesis regulated by SREBP-1c.

  6. Structural Basis of Sterol Binding by NPC2, a Lysosomal Protein Deficient in Niemann-Pick Type C2 Disease

    SciTech Connect

    Xu,S.; Benoff, B.; Liou, H.; Lobel, P.; Stock, A.

    2007-01-01

    NPC2 is a small lysosomal glycoprotein that binds cholesterol with submicromolar affinity. Deficiency in NPC2 is the cause of Niemann-Pick type C2 disease, a fatal neurovisceral disorder characterized by accumulation of cholesterol in lysosomes. Here we report the crystal structure of bovine NPC2 bound to cholesterol-3-O-sulfate, an analog that binds with greater apparent affinity than cholesterol. Structures of both apo-bound and sterol-bound NPC2 were observed within the same crystal lattice, with an asymmetric unit containing one molecule of apoNPC2 and two molecules of sterol-bound NPC2. As predicted from a previously determined structure of apoNPC2, the sterol binds in a deep hydrophobic pocket sandwiched between the two {beta}-sheets of NPC2, with only the sulfate substituent of the ligand exposed to solvent. In the two available structures of apoNPC2, the incipient ligand-binding pocket, which ranges from a loosely packed hydrophobic core to a small tunnel, is too small to accommodate cholesterol. In the presence of sterol, the pocket expands, facilitated by a slight separation of the {beta}-strands and substantial reorientation of some side chains, resulting in a perfect molding of the pocket around the hydrocarbon portion of cholesterol. A notable feature is the repositioning of two aromatic residues at the tunnel entrance that are essential for NPC2 function. The NPC2 structures provide evidence of a malleable binding site, consistent with the previously documented broad range of sterol ligand specificity.

  7. The effect of meat products enriched with plant sterols and minerals on serum lipids and blood pressure.

    PubMed

    Tapola, Niina S; Lyyra, Mari L; Karvonen, Henna M; Uusitupa, Matti I; Sarkkinen, Essi S

    2004-08-01

    The purpose of the study was to investigate the effect of non-esterified plant sterol-enriched and mineral-enriched low-fat and low-salted meat products compared with control meat products, on serum total and lipoprotein lipids and blood pressure in subjects with mildly to moderately elevated serum cholesterol concentration. A randomised, placebo-controlled, single-blind, repeated measure design was used. Altogether 21 volunteers completed the study. The study began with a pre-trial period of 1-2 weeks, which was followed by three different test periods in the following order: meat products enriched with plant sterols (1.2 g/day), potassium, calcium and magnesium (MP1); meat products with no added plant sterols and minerals (control); and meat products with plant sterols (2.1 g/day), potassium, calcium and magnesium (MP2). Each test period lasted for 3 weeks. During the MP2 period, the serum total and low-density lipoprotein cholesterol concentration decreased 4.9+/-7.5% (P<0.05) and 4.6+/-11.3% (not significant), respectively, compared with the control period. No differences in the high-density lipoprotein cholesterol and total triglyceride concentrations or in systolic blood pressure and diastolic blood pressure were found among the test periods. In conclusion, the present study showed that frankfurters and cold cuts enriched with plant sterols from tall oil, potassium, calcium and magnesium, as part of habitual Finnish diet reduced the serum total cholesterol concentration in hypercholesterolemic subjects when the intake of sitosterols was 2.1 g/day, but not with the lower dose.

  8. Inorganic nitrogen, sterols and bacterial source tracking as tools to characterize water quality and possible contamination sources in surface water.

    PubMed

    Furtula, Vesna; Osachoff, Heather; Derksen, George; Juahir, Hafizan; Colodey, Al; Chambers, Patricia

    2012-03-15

    The effects of agricultural activities on stream water quality were assessed by nitrogen analysis, further investigated by gas chromatography mass spectrometry (GC-MS) sterol analysis (including chemometric analysis), and characterized by bacterial source tracking (BST). Surface water samples were collected from five sites, throughout the agriculturally-influenced Nathan Creek watershed, British Columbia, Canada and a nearby control site between October 2005 and March 2006. From a total of 48 samples, Canadian Water Quality Guidelines were exceeded nineteen times for nitrate (NO3-; guideline value: 2.94 mg/L N) and four times for un-ionized ammonia (NH3; guideline value 0.019 mg/L N). Gas chromatography mass spectrometry single ion monitoring (GC-MS SIM) analysis of 18 sterols showed that five fecal sterols (coprostanol, episoprostanol, cholesterol, cholestanol, desmosterol) were detected at all sites except the control site (where only cholesterol, cholestanol and desmosterol were detected). Three phytosterols (campesterol, stigmasterol and β-sitosterol) were also detected at all sites while the hormone estrone was present at one site on two occasions at concentrations of 0.01 and 0.04 μg/L. Chemometric analysis (principal component analysis and cluster analysis) grouped sites based on their similarities in sterol composition. Analysis of ten sterol ratios (seven for identifying human fecal contamination and four for differentiating sources of fecal contamination) showed multiple instances of human and animal contamination for every site but the control site. Application of a Bacteroides-BST method confirmed contamination from ruminant animals, pigs and dogs in varying combinations at all impact sites. Together, these results confirmed the impact of agricultural activities on the Nathan Creek watershed and support a need for better land management practices to protect water quality and aquatic life.

  9. STRUCTURAL BASIS OF STEROL BINDING BY NPC2, A LYSOSOMAL PROTEIN DEFICIENT IN NIEMANN-PICK TYPE C2 DISEASE*

    PubMed Central

    Xu, Sujuan; Benoff, Brian; Liou, Heng-Ling; Lobel, Peter; Stock, Ann M.

    2013-01-01

    NPC2 is a small lysosomal glycoprotein that binds cholesterol with submicromolar affinity. Deficiency in NPC2 is the cause of Niemann Pick type C2 disease, a fatal neurovisceral disorder characterized by accumulation of cholesterol in lysosomes. Here we report the crystal structure of bovine NPC2 bound to cholesterol-3-O-sulfate, an analog that binds with greater apparent affinity than cholesterol. Structures of both apo- and sterol-bound NPC2 were observed within the same crystal lattice, with an asymmetric unit containing one molecule of apoNPC2 and two molecules of sterol-bound NPC2. As predicted from a previously determined structure of apoNPC2, the sterol binds in a deep hydrophobic pocket sandwiched between the two β sheets of NPC2, with only the sulfate substituent of the ligand exposed to solvent. In the two available structures of apoNPC2, the incipient ligand-binding pocket, which ranges from a loosely packed hydrophobic core to a small tunnel, is too small to accommodate cholesterol. In the presence of sterol, the pocket expands, facilitated by a slight separation of the β strands and substantial reorientation of some side chains, resulting in a perfect molding of the pocket around the hydrocarbon portion of cholesterol. A notable feature is the repositioning of two aromatic residues at the tunnel entrance that are essential for NPC2 function. The NPC2 structures provide evidence of a malleable binding site, consistent with the previously documented broad range of sterol ligand specificity. PMID:17573352

  10. Two novel C29-5beta-sterols from the stems of Opuntia dillenii.

    PubMed

    Jiang, Jianqin; Li, Yanfang; Chen, Zhen; Min, Zhida; Lou, Fengchang

    2006-12-01

    Two novel C29-5beta-sterols, opuntisterol [(24R)-24-ethyl-5beta-cholest-9-ene-6beta,12alpha-diol] (1) and opuntisteroside [(24R)-24-ethyl-6beta-[(beta-d-glucopyranosyl)oxy]-5beta-cholest-9-ene-12alpha-ol] (2), together with nine known compounds, beta-sitosterol (3), taraxerol (4), friedelin (5), methyl linoleate (6), 7-oxositosterol (7), 6beta-hydroxystigmast-4-ene-3-one (8), daucosterol (9), methyl eucomate (10) and eucomic acid (11), were isolated from the stems of Opuntia dillenii collected in Guizhou Province, China. Their structures were elucidated mainly by spectroscopic analysis. The absolute configuration of 1 were deduced from comparative 1H NMR data of the (S)- and (R)-methoxyphenyl acetate derivatives. Compounds 6-8, 10 and 11 were isolated from O. dillenii for the first time.

  11. Quantification of sterols and aliphatic alcohols in Mediterranean stone pine (Pinus pinea L.) populations.

    PubMed

    Nasri, Nizar; Fady, Bruno; Triki, Saïda

    2007-03-21

    Individual components of Pinus pinea L. oil unsaponifiable matter isolated from seven Mediterranean populations were identified and quantified. P. pinea oil unsaponifiable matter contained very high levels of phytosterols (>or=4298 mg kg-1 of total extracted lipids), of which beta-sitosterol was the most abundant (74%). Aliphatic alcohol contents were 1365 mg kg-1 of total extracted lipids, of which octacosanol was the most abundant (41%). Two alcohols (hexacosanol and octacosanol), which are usually absent in common vegetable oils, were described for P. pinea oils. There were almost no differences in the total unsaponifiable matter of the seven Mediterranean populations studied. However, sterol and aliphatic alcohol contents showed some variability, with Tunisian and Moroccan populations showing very different and higher contents.

  12. Fatty acids and sterols composition, and antioxidant activity of oils extracted from plant seeds.

    PubMed

    Kozłowska, Mariola; Gruczyńska, Eliza; Ścibisz, Iwona; Rudzińska, Magdalena

    2016-12-15

    This study determined and compared the contents of bioactive components in plant seed oils extracted with n-hexane (Soxhlet method) and chloroform/methanol (Folch method) from coriander, caraway, anise, nutmeg and white mustard seeds. Oleic acid dominated among unsaturated fatty acids in nutmeg and anise seed oils while petroselinic acid was present in coriander and caraway oils. Concerning sterols, β-sitosterol was the main component in seed oils extracted with both methods. The content of total phenolics in nutmeg, white mustard and coriander seed oils extracted with chloroform/methanol was higher than in their counterparts prepared with n-hexane. The seed oil samples extracted according to the Folch method exhibited a higher ability to scavenge DPPH radicals compared to the oil samples prepared with the Soxhlet method. DPPH values of the methanolic extracts derived from oils produced with the Folch method were also higher than in the oils extracted with n-hexane.

  13. Plant sterol oxides in functional beverages: influence of matrix and storage.

    PubMed

    González-Larena, Marina; Garcia-Llatas, Guadalupe; Clemente, Gonzalo; Barberá, Reyes; Lagarda, María Jesús

    2015-04-15

    Three plant sterol (PS)-enriched beverages, milk based fruit juice (MFJPS), fruit juice (FJPS) and milk beverage (MPS), were stored at 4, 24, or 37 °C and analysed at regular time intervals of 2 months until 6 months. PS stability was analysed from the production of phytosterol oxidation products (POPs). The β-sitosterol oxides (7α/7β-hydroxy, β/α-epoxy, triol, and 7-keto) and campesterol oxides (β/α-epoxy, and 7-keto) were detected in all beverages and at all storage times and temperatures. Total POP contents followed the order MPS≫FJPS>MFJPS. In general, the beverages showed low PS oxidation levels (<0.17%). Predictive models of POP content versus storage time were established. These models explain total POP content by over 75% and individual POP content by over 50%. We propose 7-ketositosterol and 7-ketocampesterol as PS oxidation markers during storage of beverages of this kind.

  14. New cholestane glycosides and sterols from the underground parts of Chamaelirium luteum and their cytotoxic activity.

    PubMed

    Yokosuka, Akihito; Takagi, Kenichi; Mimaki, Yoshihiro

    2013-07-01

    Six new cholestane glycosides (1, 5, 6, 10, 12, and 13) and two new sterols (9 and 11), along with five known compounds (2-4, 7, and 8), were isolated from the underground parts of Chamaelirium luteum (Liliaceae). The structures of these new compounds were determined by spectroscopic analysis and the results of hydrolytic cleavage. The isolated compounds and aglycones were evaluated for their cytotoxic activity against HL-60 human leukemia cells. Compounds 6a, 10a, 12a, 13, and 13a were cytotoxic to HL-60 cells, with IC50 values of 12.8, 9.8, 15.3, 6.2, and 10.2 µM, respectively.

  15. Topsensterols A–C, Cytotoxic Polyhydroxylated Sterol Derivatives from a Marine Sponge Topsentia sp.

    PubMed Central

    Chen, Min; Wu, Xu-Dong; Zhao, Qing; Wang, Chang-Yun

    2016-01-01

    Three new polyhydroxylated sterol derivatives topsensterols A–C (1–3) have been isolated from a marine sponge Topsentia sp. collected from the South China Sea. Their structures were elucidated by detailed analysis of the spectroscopic data, especially the NOESY spectra. Topsensterols A–C (l–3) possess novel 2β,3α,4β,6α-tetrahydroxy-14α-methyl Δ9(11) steroidal nuclei with unusual side chains. Compound 2 exhibited cytotoxicity against human gastric carcinoma cell line SGC-7901 with an IC50 value of 8.0 μM. Compound 3 displayed cytotoxicity against human erythroleukemia cell line K562 with an IC50 value of 6.0 μM. PMID:27490555

  16. GPCR production in a novel yeast strain that makes cholesterol-like sterols.

    PubMed

    Kitson, Susan M; Mullen, William; Cogdell, Richard J; Bill, Roslyn M; Fraser, Niall J

    2011-12-01

    The activities of many mammalian membrane proteins including G-protein coupled receptors are cholesterol-dependent. Unlike higher eukaryotes, yeast do not make cholesterol. Rather they make a related molecule called ergosterol. As cholesterol and ergosterol are biologically non-equivalent, the potential of yeast as hosts for overproducing mammalian membrane proteins has never been fully realised. To address this problem, we are trying to engineer a novel strain of Saccharomyces cerevisiae in which the cholesterol biosynthetic pathway of mammalian cells has been fully reconstituted. Thus far, we have created a modified strain that makes cholesterol-like sterols which has an increased capacity to make G-protein coupled receptors compared to control yeast.

  17. Segregation of sphingolipids and sterols during formation of secretory vesicles at the trans-Golgi network

    PubMed Central

    Klemm, Robin W.; Ejsing, Christer S.; Surma, Michal A.; Kaiser, Hermann-Josef; Gerl, Mathias J.; Sampaio, Julio L.; de Robillard, Quentin; Ferguson, Charles; Proszynski, Tomasz J.; Shevchenko, Andrej

    2009-01-01

    The trans-Golgi network (TGN) is the major sorting station in the secretory pathway of all eukaryotic cells. How the TGN sorts proteins and lipids to generate the enrichment of sphingolipids and sterols at the plasma membrane is poorly understood. To address this fundamental question in membrane trafficking, we devised an immunoisolation procedure for specific recovery of post-Golgi secretory vesicles transporting a transmembrane raft protein from the TGN to the cell surface in the yeast Saccharomyces cerevisiae. Using a novel quantitative shotgun lipidomics approach, we could demonstrate that TGN sorting selectively enriched ergosterol and sphingolipid species in the immunoisolated secretory vesicles. This finding, for the first time, indicates that the TGN exhibits the capacity to sort membrane lipids. Furthermore, the observation that the immunoisolated vesicles exhibited a higher membrane order than the late Golgi membrane, as measured by C-Laurdan spectrophotometry, strongly suggests that lipid rafts play a role in the TGN-sorting machinery. PMID:19433450

  18. Malformation syndromes caused by disorders of cholesterol synthesis

    PubMed Central

    Porter, Forbes D.; Herman, Gail E.

    2011-01-01

    Cholesterol homeostasis is critical for normal growth and development. In addition to being a major membrane lipid, cholesterol has multiple biological functions. These roles include being a precursor molecule for the synthesis of steroid hormones, neuroactive steroids, oxysterols, and bile acids. Cholesterol is also essential for the proper maturation and signaling of hedgehog proteins, and thus cholesterol is critical for embryonic development. After birth, most tissues can obtain cholesterol from either endogenous synthesis or exogenous dietary sources, but prior to birth, the human fetal tissues are dependent on endogenous synthesis. Due to the blood-brain barrier, brain tissue cannot utilize dietary or peripherally produced cholesterol. Generally, inborn errors of cholesterol synthesis lead to both a deficiency of cholesterol and increased levels of potentially bioactive or toxic precursor sterols. Over the past couple of decades, a number of human malformation syndromes have been shown to be due to inborn errors of cholesterol synthesis. Herein, we will review clinical and basic science aspects of Smith-Lemli-Opitz syndrome, desmosterolosis, lathosterolosis, HEM dysplasia, X-linked dominant chondrodysplasia punctata, Congenital Hemidysplasia with Ichthyosiform erythroderma and Limb Defects Syndrome, sterol-C-4 methyloxidase-like deficiency, and Antley-Bixler syndrome. PMID:20929975

  19. A Dietary Test of Putative Deleterious Sterols for the Aphid Myzus persicae

    PubMed Central

    Bouvaine, Sophie; Faure, Marie-Line; Grebenok, Robert J.; Behmer, Spencer T.; Douglas, Angela E.

    2014-01-01

    The aphid Myzus persicae displays high mortality on tobacco plants bearing a transgene which results in the accumulation of the ketosteroids cholestan-3-one and cholest-4-en-3-one in the phloem sap. To test whether the ketosteroids are the basis of the plant resistance to the aphids, M. persicae were reared on chemically-defined diets with different steroid contents at 0.1–10 µg ml−1. Relative to sterol-free diet and dietary supplements of the two ketosteroids and two phytosterols, dietary cholesterol significantly extended aphid lifespan and increased fecundity at one or more dietary concentrations tested. Median lifespan was 50% lower on the diet supplemented with cholest-4-en-3-one than on the cholesterol-supplemented diet. Aphid feeding rate did not vary significantly across the treatments, indicative of no anti-feedant effect of any sterol/steroid. Aphids reared on diets containing equal amounts of cholesterol and cholest-4-en-3-one showed fecundity equivalent to aphids on diets containing only cholesterol. Aphids were reared on diets that reproduced the relative steroid abundance in the phloem sap of the control and modified tobacco plants, and their performance on the two diet formulations was broadly equivalent. We conclude that, at the concentrations tested, plant ketosteroids support weaker aphid performance than cholesterol, but do not cause acute toxicity to the aphids. In plants, the ketosteroids may act synergistically with plant factors absent from artificial diets but are unlikely to be solely responsible for resistance of modified tobacco plants. PMID:24465993

  20. Activation of Sterol Regulatory Element Binding Factors by Fenofibrate and Gemfibrozil Stimulates Myelination in Zebrafish

    PubMed Central

    Ashikawa, Yoshifumi; Nishimura, Yuhei; Okabe, Shiko; Sasagawa, Shota; Murakami, Soichiro; Yuge, Mizuki; Kawaguchi, Koki; Kawase, Reiko; Tanaka, Toshio

    2016-01-01

    Oligodendrocytes are major myelin-producing cells and play essential roles in the function of a healthy nervous system. However, they are also one of the most vulnerable neural cell types in the central nervous system (CNS), and myelin abnormalities in the CNS are found in a wide variety of neurological disorders, including multiple sclerosis, adrenoleukodystrophy, and schizophrenia. There is an urgent need to identify small molecular weight compounds that can stimulate myelination. In this study, we performed comparative transcriptome analysis to identify pharmacodynamic effects common to miconazole and clobetasol, which have been shown to stimulate myelination by mouse oligodendrocyte progenitor cells (OPCs). Of the genes differentially expressed in both miconazole- and clobetasol-treated mouse OPCs compared with untreated cells, we identified differentially expressed genes (DEGs) common to both drug treatments. Gene ontology analysis revealed that these DEGs are significantly associated with the sterol biosynthetic pathway, and further bioinformatics analysis suggested that sterol regulatory element binding factors (SREBFs) might be key upstream regulators of the DEGs. In silico screening of a public database for chemicals associated with SREBF activation identified fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist, as a drug that increases the expression of known SREBF targets, raising the possibility that fenofibrate may also stimulate myelination. To test this, we performed in vivo imaging of zebrafish expressing a fluorescent reporter protein under the control of the myelin basic protein (mbp) promoter. Treatment of zebrafish with fenofibrate significantly increased expression of the fluorescent reporter compared with untreated zebrafish. This increase was attenuated by co-treatment with fatostatin, a specific inhibitor of SREBFs, confirming that the fenofibrate effect was mediated via SREBFs. Furthermore, incubation of zebrafish

  1. Conversion of Exogenous Cholesterol into Glycoalkaloids in Potato Shoots, Using Two Methods for Sterol Solubilisation

    PubMed Central

    Petersson, Erik V.; Nahar, Nurun; Dahlin, Paul; Broberg, Anders; Tröger, Rikard; Dutta, Paresh C.; Jonsson, Lisbeth; Sitbon, Folke

    2013-01-01

    Steroidal glycoalkaloids (SGA) are toxic secondary metabolites naturally occurring in the potato, as well as in certain other Solanaceous plant species, such as tomato, eggplant and pepper. To investigate the steroidal origin of SGA biosynthesis, cut potato shoots were fed cholesterol labelled with deuterium (D) in the sterol ring structure (D5- or D6-labelled), or side chain (D7-labelled), and analysed after three or five weeks. The labelled cholesterol and presence of D-labelled SGA were analysed by GC-MS and LC-MS/MS, respectively. When feeding D-labelled cholesterol solubilised in Tween-80, labelled cholesterol in free form became present in both leaves and stems, although the major part was recovered as steryl esters. Minor amounts of D-labelled SGA (α-solanine and α-chaconine) were identified in cholesterol-treated shoots, but not in blank controls, or in shoots fed D6-27-hydroxycholesterol. Solubilising the labelled cholesterol in methyl-β-cyclodextrin instead of Tween-80 increased the levels of labelled SGA up to 100-fold, and about 1 mole% of the labelled cholesterol was recovered as labelled SGA in potato leaves. Both side chain and ring structure D labels were retained in SGA, showing that the entire cholesterol molecule is converted to SGA. However, feeding side chain D7-labelled cholesterol resulted in D5-labelled SGA, indicating that two hydrogen atoms were released during formation of the SGA nitrogen-containing ring system. Feeding with D7-sitosterol did not produce any labelled SGA, indicating that cholesterol is a specific SGA precursor. In conclusion, we have demonstrated a superior performance of methyl-β-cyclodextrin for delivery of cholesterol in plant tissue feeding experiments, and given firm evidence for cholesterol as a specific sterol precursor of SGA in potato. PMID:24349406

  2. Sterol glycosides and cerebrosides accumulate in Pichia pastoris, Rhynchosporium secalis and other fungi under normal conditions or under heat shock and ethanol stress.

    PubMed

    Sakaki, T; Zähringer, U; Warnecke, D C; Fahl, A; Knogge, W; Heinz, E

    2001-06-01

    The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans, Pichia pastoris and Pichia anomala, as well as in the six fungal species Sordaria macrospora, Pyrenophora teres, Ustilago maydis, Acremonium chrysogenum, Penicillium olsonii and Rhynchosporium secalis. Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis, S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are beta-glucosyl ceramides consisting of a saturated alpha-hydroxy or non-hydroxy fatty acid and a Delta4,8-diunsaturated, C9-methyl-branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol-beta-D-glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae, new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the

  3. Formation of Plant Sterol Oxidation Products in Foods during Baking and Cooking Using Margarine without and with Added Plant Sterol Esters.

    PubMed

    Lin, Yuguang; Knol, Diny; Menéndez-Carreño, María; Blom, Wendy A M; Matthee, Joep; Janssen, Hans-Gerd; Trautwein, Elke A

    2016-01-27

    Plant sterols (PS) in foods are subject to thermal oxidation to form PS oxidation products (POP). This study measured POP contents of 19 foods prepared by typical household baking and cooking methods using margarines without (control) and with 7.5% added PS (as 12.5% PS-esters, PS-margarine). Median POP contents per portion size of cooked foods were 0.57 mg (range 0.05-1.11 mg) with control margarine versus 1.42 mg (range 0.08-20.5 mg) with PS-margarine. The oxidation rate of PS (ORP) was 0.50% (median) with the PS-margarine and 3.66% with the control margarine. Using the PS-margarine, microwave-cooked codfish had the lowest POP content, with 0.08 mg per portion, while shallow-fried potatoes had the highest POP content, 20.5 mg per portion. Median POP contents in cookies, muffins, banana bread, and sponge cake baked with the control or PS-margarine were 0.12 mg (range 0.11-0.21 mg) and 0.24 mg (range 0.19-0.60 mg) per portion, with a corresponding ORP of 1.38% and 0.06%, respectively. POP contents in all the cooked and baked foods did not exceed 20.5 mg per typical portion size. A wide variation in the distribution of individual POP among different foods existed, with 7-keto-PS and 5,6-epoxy-PS being the major oxidation products.

  4. Chemical Synthesis of Proteins

    PubMed Central

    Nilsson, Bradley L.; Soellner, Matthew B.; Raines, Ronald T.

    2010-01-01

    Proteins have become accessible targets for chemical synthesis. The basic strategy is to use native chemical ligation, Staudinger ligation, or other orthogonal chemical reactions to couple synthetic peptides. The ligation reactions are compatible with a variety of solvents and proceed in solution or on a solid support. Chemical synthesis enables a level of control on protein composition that greatly exceeds that attainable with ribosome-mediated biosynthesis. Accordingly, the chemical synthesis of proteins is providing previously unattainable insight into the structure and function of proteins. PMID:15869385

  5. Inoculation of the nonlegume Capsicum annuum L. with Rhizobium strains. 2. Changes in sterols, triterpenes, fatty acids, and volatile compounds.

    PubMed

    Silva, Luís R; Azevedo, Jessica; Pereira, Maria J; Carro, Lorena; Velazquez, Encarna; Peix, Alvaro; Valentão, Patrícia; Andrade, Paula B

    2014-01-22

    Peppers (Capsicum spp.) are consumed worldwide, imparting flavor, aroma, and color to foods, additionally containing high concentrations of biofunctional compounds. This is the first report about the effect of the inoculation of two Rhizobium strains on sterols, triterpenes, fatty acids, and volatile compounds of leaves and fruits of pepper (Capsicum annuum L.) plants. Generally, inoculation with strain TVP08 led to the major changes, being observed a decrease of sterols and triterpenes and an increase of fatty acids, which are related to higher biomass, growth, and ripening of pepper fruits. The increase of volatile compounds may reflect the elicitation of plant defense after inoculation, since the content on methyl salicylate was significantly increased in inoculated material. The findings suggest that inoculation with Rhizobium strains may be employed to manipulate the content of interesting metabolites in pepper leaves and fruits, increasing potential health benefits and defense abilities of inoculated plants.

  6. The response of the grape berry moth (Lobesia botrana) to a dietary phytopathogenic fungus (Botrytis cinerea): the significance of fungus sterols.

    PubMed

    Mondy; Corio-Costet

    2000-12-01

    A Tortricidae (Lobesia botrana) has a mutualistic relationship with the fungus (Botrytis cinerea). In this study, we investigated the growth, survival, fecundity and amount of sterols and steroids in larvae of this vineyard pest reared on artificial diets containing mycelium (3%) or purified sterols (0.01%) of the phytopathogenic fungus. Two principal questions related to the physiological and biochemical basis of this mutualistic relationship were addressed: (1) how the fungus influences growth, survival, fecundity, sterol and steroid contents of the insect and (2) are fungal sterols involved in the biochemical basis of mutualism? The presence of fungus in the diet led to a decrease of total duration of larval development (mean gain 5.1-9.4 days compared to the total duration in control of 42.9 days), an increase in survival (mean gain 50-76.3%) and fecundity (gain of 94-102%). These positive effects of the fungus on the biology and physiology of the insect were directly correlated to the presence of fungal sterols in the diet. Fungal sterols are one of the biochemical basis of the mutualistic relationship between L. botrana and B. cinerea.

  7. Sterol Composition and Biosynthetic Genes of Vitrella brassicaformis, a Recently Discovered Chromerid: Comparison to Chromera velia and Phylogenetic Relationship with Apicomplexan Parasites.

    PubMed

    Khadka, Manoj; Salem, Mohamed; Leblond, Jeffrey D

    2015-01-01

    Vitrella brassicaformis is the second discovered species in the Chromerida, and first in the family Vitrellaceae. Chromera velia, the first discovered species, forms an independent photosynthetic lineage with V. brassicaformis, and both are closely related to peridinin-containing dinoflagellates and nonphotosynthetic apicomplexans; both also show phylogenetic closeness with red algal plastids. We have utilized gas chromatography/mass spectrometry to identify two free sterols, 24-ethylcholest-5-en-3β-ol, and a minor unknown sterol which appeared to be a C(28:4) compound. We have also used RNA Seq analysis to identify seven genes found in the nonmevalonate/methylerythritol pathway (MEP) for sterol biosynthesis. Subsequent genome analysis of V. brassicaformis showed the presence of two mevalonate (MVA) pathway genes, though the genes were not observed in the transcriptome analysis. Transcripts from four genes (dxr, ispf, ispd, and idi) were selected and translated into proteins to study the phylogenetic relationship of sterol biosynthesis in V. brassicaformis and C. velia to other groups of algae and apicomplexans. On the basis of our genomic and transcriptomic analyses, we hypothesize that the MEP pathway was the primary pathway that apicomplexans used for sterol biosynthesis before they lost their sterol biosynthesis ability, although contribution of the MVA pathway cannot be discounted.

  8. Applications of the Vitamin D sterol-Vitamin D receptor (VDR) conformational ensemble model.

    PubMed

    Mizwicki, Mathew T; Bishop, June E; Norman, Anthony W

    2005-01-01

    Over the past 20 years much has been learned about the cellular actions of the steroid hormone 1alpha,25(OH)2-Vitamin D3 (1,25D). Perhaps most importantly structure-function studies led to the discovery that different chemical and physical features of 1,25D are preferred to initiate either exonuclear, non-genomic or endonuclear, genomic cellular signaling. It is well documented that both a 1alpha-OH and 25-OH, and a 6-s-trans, bowl-shaped, sterol conformation are absolutely required for efficient gene transcription, while 6-s-cis locked analogs and 1-deoxy, 25(OH)D3 metabolites activate a variety of non-genomic, rapid responses. These results and the observation that S237 (helix-3; H3) and R274 (H5) are the most static residues in the human 1,25D-Vitamin D receptor (VDR) X-ray construct (see B-values in pdb: 1DB1) and form H-bonds with the 1alpha-OH of 1,25D in the X-ray, genomic pocket (G-pocket), provided the basis for the molecular modeling experiments that led to the discovery of a putative VDR alternative ligand binding pocket (A-pocket). The conformational ensemble model generated from the in silico results provides an explanation for how the VDR can function as a receptor propagating both genomic and non-genomic signaling events. In this report the theoretical gating properties controlling ligand access to the A- and G-pockets will be compared and the model will be used to provide a molecular explanation for the confusing structure-function results pertaining to 1,25D, its side-chain metabolite, 23S,25R-1alpha,25(OH)2-D3-26,23-lactone (BS), and its synthetic two side-chain analog, 21-(3'-hydroxy-3'-methylbutyl)-1alpha,25(OH)2-D3 (KH or Gemini). In addition, evidence that the model is consistent with the pH requirement for Vitamin D sterol-VDR crystallization will be presented.

  9. Faecal pH, bile acid and sterol concentrations in premenopausal Indian and white vegetarians compared with white omnivores.

    PubMed

    Reddy, S; Sanders, T A; Owen, R W; Thompson, M H

    1998-06-01

    Faecal bulk, pH, water content, the concentrations of neutral sterols and bile acids and dietary intakes were measured in twenty-two Indian vegetarian, twenty-two white omnivorous and eighteen white vegetarian premenopausal women. Faecal bulk and water content were greater and pH lower in the Indian vegetarians. Total faecal animal sterol and coprostanol concentrations expressed on a dry-weight basis were lower in the vegetarians compared with the omnivores. The faecal sterol concentrations were correlated with dietary cholesterol intake. Primary bile acids were detected in six Indian vegetarians, two white vegetarians and two white omnivores; secondary bile acids were detected in all the white omnivores and vegetarian subjects but not in two of the Indian vegetarians. Total faecal free bile acid and conjugated bile acid concentrations were lower in the white vegetarians compared with the omnivores. Faecal lithocholic acid concentrations were lower in both Indian and white vegetarians. The lithocholic: deoxycholic acid ratio and coprostanol: total animal sterols ratio were significantly lower in the Indian vegetarians compared with the omnivores. Both ratios were positively correlated with faecal pH. Stepwise multiple regression analyses were undertaken in order to identify which nutrients influenced faecal pH, lithocholic and deoxycholic acid concentrations. The intakes of starch and dietary fibre were negatively associated with faecal concentrations of lithocholic and deoxycholic acid. Starch intake alone was negatively associated with faecal pH. The results of this study confirm that diets high in dietary fibre decrease faecal bile acid concentrations and suggest that the complex carbohydrates present in Indian vegetarian diets influence faecal pH and inhibit the degradation of faecal steroids.

  10. Expression of C-5 sterol desaturase from an edible mushroom in fisson yeast enhances its ethanol and thermotolerance.

    PubMed

    Kamthan, Ayushi; Kamthan, Mohan; Datta, Asis

    2017-01-01

    Bioethanol is an environment friendly and renewable source of energy produced by the fermentation of agricultural raw material by a variety of microorganisms including yeast. Obtaining yeast strains that are tolerant to stresses like high levels of ethanol and high temperature is highly desirable as it reduces cost and increases yield during bioethanol production. Here, we report that heterologous expression of C-5 Sterol desaturase (FvC5SD)-an ergosterol biosynthesis enzyme from an edible mushroom Flammulina velutipes in fission yeast, not only imparts increased thermotolerance but also tolerance towards high ethanol concentration and low pH. This tolerance could be attributed to an increase of ≈1.5 fold in the level of ergosterol and oleic acid (C-18 unsaturated fatty acid) as analysed by gas chromatography- mass spectrometry. FvC5SD is a membrane localized iron binding enzyme that introduces double bond at C-5 position into the Δ7-sterol substrates to yield Δ5, 7- sterols as products. In F. velutipes, FvC5SD transcript was observed to be upregulated by ≈5 fold under low pH condition and by ≈ 9 folds and ≈5 fold at 40°C and 4°C respectively when compared to normal growth temperature of 23°C. Besides, susceptibility to cell wall inhibiting drugs like Congo red and Calcoflour white was also found to increase in FvC5SD expressing S. pombe strain. Alteration in membrane sterol and fatty acid composition could also lead to increase in susceptibility to cell wall inhibiting drugs. Thus, this study has immense industrial application and can be employed to ensure competitiveness of fermentation process.

  11. Investigating Sterol and Redox Regulation of the Ion Channel Activity of CLIC1 Using Tethered Bilayer Membranes.

    PubMed

    Al Khamici, Heba; Hossain, Khondher R; Cornell, Bruce A; Valenzuela, Stella M

    2016-12-08

    The Chloride Intracellular Ion Channel (CLIC) family consists of six conserved proteins in humans. These are a group of enigmatic proteins, which adopt both a soluble and membrane bound form. CLIC1 was found to be a metamorphic protein, where under specific environmental triggers it adopts more than one stable reversible soluble structural conformation. CLIC1 was found to spontaneously insert into cell membranes and form chloride ion channels. However, factors that control the structural transition of CLIC1 from being an aqueous soluble protein into a membrane bound protein have yet to be adequately described. Using tethered bilayer lipid membranes and electrical impedance spectroscopy system, herein we demonstrate that CLIC1 ion channel activity is dependent on the type and concentration of sterols in bilayer membranes. These findings suggest that membrane sterols play an essential role in CLIC1's acrobatic switching from a globular soluble form to an integral membrane form, promoting greater ion channel conductance in membranes. What remains unclear is the precise nature of this regulation involving membrane sterols and ultimately determining CLIC1's membrane structure and function as an ion channel. Furthermore, our impedance spectroscopy results obtained using CLIC1 mutants, suggest that the residue Cys24 is not essential for CLIC1's ion channel function. However Cys24 does appear important for optimal ion channel activity. We also observe differences in conductance between CLIC1 reduced and oxidized forms when added to our tethered membranes. Therefore, we conclude that both membrane sterols and redox play a role in the ion channel activity of CLIC1.

  12. Investigating Sterol and Redox Regulation of the Ion Channel Activity of CLIC1 Using Tethered Bilayer Membranes

    PubMed Central

    Al Khamici, Heba; Hossain, Khondker R.; Cornell, Bruce A.; Valenzuela, Stella M.

    2016-01-01

    The Chloride Intracellular Ion Channel (CLIC) family consists of six conserved proteins in humans. These are a group of enigmatic proteins, which adopt both a soluble and membrane bound form. CLIC1 was found to be a metamorphic protein, where under specific environmental triggers it adopts more than one stable reversible soluble structural conformation. CLIC1 was found to spontaneously insert into cell membranes and form chloride ion channels. However, factors that control the structural transition of CLIC1 from being an aqueous soluble protein into a membrane bound protein have yet to be adequately described. Using tethered bilayer lipid membranes and electrical impedance spectroscopy system, herein we demonstrate that CLIC1 ion channel activity is dependent on the type and concentration of sterols in bilayer membranes. These findings suggest that membrane sterols play an essential role in CLIC1’s acrobatic switching from a globular soluble form to an integral membrane form, promoting greater ion channel conductance in membranes. What remains unclear is the precise nature of this regulation involving membrane sterols and ultimately determining CLIC1’s membrane structure and function as an ion channel. Furthermore, our impedance spectroscopy results obtained using CLIC1 mutants, suggest that the residue Cys24 is not essential for CLIC1’s ion channel function. However Cys24 does appear important for optimal ion channel activity. We also observe differences in conductance between CLIC1 reduced and oxidized forms when added to our tethered membranes. Therefore, we conclude that both membrane sterols and redox play a role in the ion channel activity of CLIC1. PMID:27941637

  13. Expression of C-5 sterol desaturase from an edible mushroom in fisson yeast enhances its ethanol and thermotolerance

    PubMed Central

    Kamthan, Ayushi; Kamthan, Mohan; Datta, Asis

    2017-01-01

    Bioethanol is an environment friendly and renewable source of energy produced by the fermentation of agricultural raw material by a variety of microorganisms including yeast. Obtaining yeast strains that are tolerant to stresses like high levels of ethanol and high temperature is highly desirable as it reduces cost and increases yield during bioethanol production. Here, we report that heterologous expression of C-5 Sterol desaturase (FvC5SD)—an ergosterol biosynthesis enzyme from an edible mushroom Flammulina velutipes in fission yeast, not only imparts increased thermotolerance but also tolerance towards high ethanol concentration and low pH. This tolerance could be attributed to an increase of ≈1.5 fold in the level of ergosterol and oleic acid (C-18 unsaturated fatty acid) as analysed by gas chromatography- mass spectrometry. FvC5SD is a membrane localized iron binding enzyme that introduces double bond at C-5 position into the Δ7-sterol substrates to yield Δ5, 7- sterols as products. In F. velutipes, FvC5SD transcript was observed to be upregulated by ≈5 fold under low pH condition and by ≈ 9 folds and ≈5 fold at 40°C and 4°C respectively when compared to normal growth temperature of 23°C. Besides, susceptibility to cell wall inhibiting drugs like Congo red and Calcoflour white was also found to increase in FvC5SD expressing S. pombe strain. Alteration in membrane sterol and fatty acid composition could also lead to increase in susceptibility to cell wall inhibiting drugs. Thus, this study has immense industrial application and can be employed to ensure competitiveness of fermentation process. PMID:28278249

  14. Modulation of Retinoic Acid Receptor-related Orphan Receptor α and γ Activity by 7-Oxygenated Sterol Ligands*

    PubMed Central

    Wang, Yongjun; Kumar, Naresh; Solt, Laura A.; Richardson, Timothy I.; Helvering, Leah M.; Crumbley, Christine; Garcia-Ordonez, Ruben D.; Stayrook, Keith R.; Zhang, Xi; Novick, Scott; Chalmers, Michael J.; Griffin, Patrick R.; Burris, Thomas P.

    2010-01-01

    The retinoic acid receptor-related orphan receptors α and γ (RORα (NR1F1) and RORγ (NR1F3)) are orphan nuclear receptors and perform critical roles in regulation of development, metabolism, and immune function. Cholesterol and cholesterol sulfate have been suggested to be RORα ligands, but the physiological significance is unclear. To date, no endogenous RORγ ligands have been described. Here, we demonstrate that 7-oxygenated sterols function as high affinity ligands for both RORα and RORγ by directly binding to their ligand-binding domains (Ki ∼20 nm), modulating coactivator binding, and suppressing the transcriptional activity of the receptors. One of the 7-oxygenated sterols, 7α-hydroxycholesterol (7α-OHC), serves as a key intermediate in bile acid metabolism, and we show that 7α-OHC modulates the expression of ROR target genes, including Glc-6-Pase and phosphoenolpyruvate carboxykinase, in an ROR-dependent manner. Furthermore, glucose output from hepatocytes is suppressed by 7α-OHC functioning as an RORα/γ ligand. Thus, RORα and RORγ are ligand-regulated members of the NR superfamily and may serve as sensors for 7-oxygenated sterols. PMID:19965867

  15. Application of pressurized fluid extraction technique in the gas chromatography-mass spectrometry determination of sterols from marine sediment samples.

    PubMed

    Li, Donghao; Dong, Meihua; Shim, Won Joon; Kannan, Narayanan

    2007-08-10

    In order to determine steroid compounds in GC/MS an analytical method using pressurized fluid extraction (PFE) was developed. While extracting in-house reference material (coastal sediment) typical recovery in PFE ranged from 80 to 120% (+/-2.5-14.5) and the average extraction yield in PFE in comparison to conventional soxhlet extraction was 115%. In particular, the PFE showed higher extraction efficiency for C29 and dien sterols. Optimizing parameters such as temperature and pressure is critical in achieving this efficiency. Sterols in the sediment were derivatized with silyl reagent BSTFA in acetone for the final determination. A short column florisil cleanup offered the best separation of the GC/MS sensitive derivatives from co-contaminants. Thirty-three coastal sediment samples were analyzed using PFE and Soxhlet extraction methods. The results on extraction efficiency, silyl derivatization kinetics and purification efficiency demonstrated that PFE is far superior in extracting sterols from sediment samples. It is simple, fast, efficient and amenable for automation.

  16. Partially hydrolyzed guar gums reduce dietary fatty acid and sterol absorption in guinea pigs independent of viscosity.

    PubMed

    Santas, Jonathan; Espadaler, Jordi; Cuñé, Jordi; Rafecas, Magda

    2012-07-01

    This study investigated the effect of two partially hydrolyzed guar gums (PHGG) on fatty acid and sterol excretion. PHGG were obtained by chemical hydrolysis of guar gum (GG) with H(2)O:EtOH (1:1) at 100 °C for 1 h (PHGG1) or 2 h (PHGG2). The viscosity of the PHGG in a 1 % (w/v) aqueous solution corresponded to that of a pseudoplastic fluid and was higher for PHGG1 than PHGG2. Guinea pigs (n = 8 per group) were fed high fat diets (17/100 g) that contained 12/100 g of cellulose, PHGG1, or PHGG2 for 4 weeks. Despite the differences in viscosity, the two PHGG exerted similar physiological effects. Compared to the control cellulose group, the body weight gain was lower in animals fed PHGG, although no effect on food consumption was observed. PHGG increased the excretion of fatty acids and neutral sterols, but not bile acids. Consumption of PHGG did not alter the fecal fatty acid profile, while intestinal bioconversion of sterols tended to increase in response to PHGG2. A reduction in the viscosity within the range tested did not correlate with losses in the hypocholesterolemic capacity of PHGG as both were effective in reducing plasma cholesterol. Thus, we conclude that the chemical hydrolysis of guar gum renders the gum suitable for inclusion in food products without significantly altering its beneficial health effects.

  17. Genetic Variation in Plant CYP51s Confers Resistance against Voriconazole, a Novel Inhibitor of Brassinosteroid-Dependent Sterol Biosynthesis

    PubMed Central

    Rozhon, Wilfried; Husar, Sigrid; Kalaivanan, Florian; Khan, Mamoona; Idlhammer, Markus; Shumilina, Daria; Lange, Theo; Hoffmann, Thomas; Schwab, Wilfried; Fujioka, Shozo; Poppenberger, Brigitte

    2013-01-01

    Brassinosteroids (BRs) are plant steroid hormones with structural similarity to mammalian sex steroids and ecdysteroids from insects. The BRs are synthesized from sterols and are essential regulators of cell division, cell elongation and cell differentiation. In this work we show that voriconazole, an antifungal therapeutic drug used in human and veterinary medicine, severely impairs plant growth by inhibiting sterol-14α-demethylation and thereby interfering with BR production. The plant growth regulatory properties of voriconazole and related triazoles were identified in a screen for compounds with the ability to alter BR homeostasis. Voriconazole suppressed growth of the model plant Arabidopsis thaliana and of a wide range of both monocotyledonous and dicotyledonous plants. We uncover that voriconazole toxicity in plants is a result of a deficiency in BRs that stems from an inhibition of the cytochrome P450 CYP51, which catalyzes a step of BR-dependent sterol biosynthesis. Interestingly, we found that the woodland strawberry Fragaria vesca, a member of the Rosaceae, is naturally voriconazole resistant and that this resistance is conferred by the specific CYP51 variant of F. vesca. The potential of voriconazole as a novel tool for plant research is discussed. PMID:23335967

  18. A comprehensive method for extraction and quantitative analysis of sterols and secosteroids from human plasma[S

    PubMed Central

    McDonald, Jeffrey G.; Smith, Daniel D.; Stiles, Ashlee R.; Russell, David W.

    2012-01-01

    We describe the development of a method for the extraction and analysis of 62 sterols, oxysterols, and secosteroids from human plasma using a combination of HPLC-MS and GC-MS. Deuterated standards are added to 200 μl of human plasma. Bulk lipids are extracted with methanol:dichloromethane, the sample is hydrolyzed using a novel procedure, and sterols and secosteroids are isolated using solid-phase extraction (SPE). Compounds are resolved on C18 core-shell HPLC columns and by GC. Sterols and oxysterols are measured using triple quadrupole mass spectrometers, and lathosterol is measured using GC-MS. Detection for each compound measured by HPLC-MS was ∪ 1 ng/ml of plasma. Extraction efficiency was between 85 and 110%; day-to-day variability showed a relative standard error of <10%. Numerous oxysterols were detected, including the side chain oxysterols 22-, 24-, 25-, and 27-hydroxycholesterol, as well as ring-structure oxysterols 7α- and 4β-hydroxycholesterol. Intermediates from the cholesterol biosynthetic pathway were also detected, including zymosterol, desmosterol, and lanosterol. This method also allowed the quantification of six secosteroids, including the 25-hydroxylated species of vitamins D2 and D3. Application of this method to plasma samples revealed that at least 50 samples could be extracted in a routine day. PMID:22517925

  19. Two C4-sterol methyl oxidases (Erg25) catalyse ergosterol intermediate demethylation and impact environmental stress adaptation in Aspergillus fumigatus

    PubMed Central

    Blosser, Sara J.; Merriman, Brittney; Grahl, Nora; Chung, Dawoon

    2014-01-01

    The human pathogen Aspergillus fumigatus adapts to stress encountered in the mammalian host as part of its ability to cause disease. The transcription factor SrbA plays a significant role in this process by regulating genes involved in hypoxia and low-iron adaptation, antifungal drug responses and virulence. SrbA is a direct transcriptional regulator of genes encoding key enzymes in the ergosterol biosynthesis pathway, including erg25A and erg25B, and ΔsrbA accumulates C4-methyl sterols, suggesting a loss of Erg25 activity [C4-sterol methyl oxidase (SMO)]. Characterization of the two genes encoding SMOs in Aspergillus fumigatus revealed that both serve as functional C4-demethylases, with Erg25A serving in a primary role, as Δerg25A accumulates more C4-methyl sterol intermediates than Δerg25B. Single deletion of these SMOs revealed alterations in canonical ergosterol biosynthesis, indicating that ergosterol may be produced in an alternative fashion in the absence of SMO activity. A Δerg25A strain displayed moderate susceptibility to hypoxia and the endoplasmic reticulum stress-inducing agent DTT, but was not required for virulence in murine or insect models of invasive aspergillosis. Inducing expression of erg25A partially restored the hypoxia growth defect of ΔsrbA. These findings implicated Aspergillus fumigatus SMOs in the maintenance of canonical ergosterol biosynthesis and indicated an overall involvement in the fungal stress response. PMID:25107308

  20. Association Study Between Metabolic Syndrome and rs8066560 Polymorphism in the Promoter Region of Sterol Regulatory Element-binding Transcription Factor 1 Gene in Iranian Children and Adolescents

    PubMed Central

    Miranzadeh-Mahabadi, Hajar; Emadi-Baygi, Modjtaba; Nikpour, Parvaneh; Kelishadi, Roya

    2016-01-01

    Background: Metabolic syndrome (MetS) is a prevalent disorder in pediatric age groups, described by a combination of genetic and environmental factors. Sterol regulatory element-binding transcription factor 1 (SREBF-1) induces the expression of a family of genes involved in fatty acid synthesis. Moreover, dysregulation of miR-33b, which is located within the intron 17 of the SREBF-1 gene, disrupts fatty acid oxidation and insulin signaling, thus leading to MetS. The aim of the present study was to investigate the association between SREBF-1 rs8066560 polymorphism and MetS in Iranian children and adolescents. Methods: This study includes 100 MetS and 100 normal individuals aged 9–19 years. Anthropological and biochemical indexes were measured. The -1099G > A polymorphism was genotyped by TaqMan real-time polymerase chain reaction. Results: Significant differences were observed in anthropometric measurements and lipid profiles between MetS and normal children. There were no differences in the genotype frequencies or allele distribution for -1099G > A polymorphism between MetS and control groups. High-density lipoprotein cholesterol levels were significantly higher in the MetS GG group than in the A allele carrier group. The genotype AA controls had significantly increased cholesterol and low-density lipoprotein cholesterol levels than AG genotypes. By logistic regression using different genetic models, no significant association was observed between SREBF-1 rs8066560 polymorphism and the risk of MetS. Conclusions: We conclude that the -1099G > A variant on SREBF-1 gene associated with serum lipid profiles, however, it may not be a major risk factor for the MetS in Iranian children and adolescents. PMID:27076879

  1. Sterol O-Acyltransferase 2 Contributes to the Yolk Cholesterol Trafficking during Zebrafish Embryogenesis

    PubMed Central

    Lee, Yen-Hua; HuangFu, Wei-Chun

    2016-01-01

    To elucidate whether Sterol O-acyltransferase (Soat) mediates the absorption and transportation of yolk lipids to the developing embryo, zebrafish soat1 and soat2 were cloned and studied. In the adult zebrafish, soat1 was detected ubiquitously while soat2 mRNA was detected specifically in the liver, intestine, brain and testis. Whole mount in situ hybridization demonstrated that both soat1 and soat2 expressed in the yolk syncytial layer, hatching gland and developing cardiovascular as well as digestive systems, suggesting that Soats may play important roles in the lipid trafficking and utilization during embryonic development. The enzymatic activity of zebrafish Soat2 was confirmed by Oil Red O staining in the HEK293 cells overexpressing this gene, and could be quenched by Soat2 inhibitor Pyripyropene A (PPPA). The zebrafish embryos injected with PPPA or morpholino oligo against soat2 in the yolk showed significantly larger yolk when compared with wild-type embryos, especially at 72 hpf, indicating a slower rate of yolk consumption. Our result indicated that zebrafish Soat2 is catalytically active in synthesizing cholesteryl esters and contributes to the yolk cholesterol trafficking during zebrafish embryogenesis. PMID:27936201

  2. Submicellar bile salts stimulate phosphatidylcholine transfer activity of sterol carrier protein 2.

    PubMed

    Leonard, A N; Cohen, D E

    1998-10-01

    To explore a potential role for sterol carrier protein 2 (SCP2, also known as non-specific lipid transfer protein) in hepatocellular phospholipid trafficking, we examined the influence of submicellar bile salt concentrations on phosphatidylcholine (PC) transfer activity of SCP2. We measured rate constants for first-order transfer of sn-1 palmitoyl, sn-2 parinaroyl PC, a naturally fluorescent self-quenching phospholipid between model membranes. Purified bovine liver SCP2 promoted transfer of PC from donor to acceptor small unilamellar vesicles. Taurine- and glycine-conjugated bile salts (anionic steroid detergent-like molecules), at concentrations well below their critical micellar concentrations, stimulated PC transfer activity of SCP2 80- to 140-fold. Rate constants increased in proportion to bile salt concentration, temperature, and bile salt-membrane binding affinity. Sodium taurofusidate, a conjugated fungal bile salt analog, also activated PC transfer whereas no effect was observed with the anionic and non-ionic straight chain detergents sodium dodecyl sulfate and octylglucoside, respectively. Thermodynamic and kinetic analyses of PC transfer support a mechanism in which bile salts stimulate SCP2 activity by partitioning into donor vesicles and enhancing membrane association of SCP2. These results imply that under physiological conditions, SCP2 may contribute to hepatocellular selection and transport of biliary PCs.

  3. Interaction of polyene antibiotics with sterols in phosphatidylcholine bilayer membranes as studied by spin probes.

    PubMed

    Ohki, K; Nozawa, Y; Ohnishi, S I

    1979-06-13

    Interaction of filipin and amphotericin B with sterols in phosphatidylcholine membranes has been studied using various spin probes; epiandrosterone, cholestanone, phosphatidylcholine with 12-nitroxide or 5-nitroxide stearate attached to 2 position and also with tempocholine at the head group. Filipin caused increase in the fluidity of cholesterol-containing phosphatidylcholine membranes near the center, while it rather decreased the fluidity near the polar surface. On the other hand, amphotericin B did not apparently affect the fluidity. In the electron spin resonance spectrum of steriod spin probes in the antibiotic-containing membranes, both bound and free signals were observed and the association constant was calculated from the siganal intensity. In the binding of steriods with filipin, both 3 and 17 positions were involved, while the 17 positions was less involved in the binding with amphotericin B. Phase change in the host membrane markedly affected the interaction of filipin with epiandrosterone probe. The bound fraction jumped from 0.4 to 0.8 on going to the crystalline state and increased further with decrease in temperature. The overall splitting of the bound signal also increased on lowering the temperature below phase transition. This change was attributed to aggregate formation of filipin-steriod complexes in the crystalline state. On the other hand, effect of phase transition was much smaller on the interaction of amphotericin B with the steriod probe.

  4. Expression of a fungal sterol desaturase improves tomato drought tolerance, pathogen resistance and nutritional quality

    PubMed Central

    Kamthan, Ayushi; Kamthan, Mohan; Azam, Mohammad; Chakraborty, Niranjan; Chakraborty, Subhra; Datta, Asis

    2012-01-01

    Crop genetic engineering mostly aims at improving environmental stress (biotic and abiotic) tolerance as well as nutritional quality. Empowering a single crop with multiple traits is highly demanding and requires manipulation of more than one gene. However, we report improved drought tolerance and fungal resistance along with the increased iron and polyunsaturated fatty acid content in tomato by expressing a single gene encoding C-5 sterol desaturase (FvC5SD) from an edible fungus Flammulina velutipes. FvC5SD is an iron binding protein involved in ergosterol biosynthesis. Morphological and biochemical analyses indicated ≈23% more epicuticular wax deposition in leaves of transgenic plants that provides an effective waterproof barrier resulting in improved protection from drought and infection by phytopathogenic fungus Sclerotinia sclerotiorum. Furthermore, the transgenic fruits have improved nutritional value attributed to enhanced level of beneficial PUFA and 2-3 fold increase in total iron content. This strategy can be extended to other economically important crops. PMID:23230516

  5. MicroRNA-33 regulates sterol regulatory element-binding protein 1 expression in mice

    PubMed Central

    Horie, Takahiro; Nishino, Tomohiro; Baba, Osamu; Kuwabara, Yasuhide; Nakao, Tetsushi; Nishiga, Masataka; Usami, Shunsuke; Izuhara, Masayasu; Sowa, Naoya; Yahagi, Naoya; Shimano, Hitoshi; Matsumura, Shigenobu; Inoue, Kazuo; Marusawa, Hiroyuki; Nakamura, Tomoyuki; Hasegawa, Koji; Kume, Noriaki; Yokode, Masayuki; Kita, Toru; Kimura, Takeshi; Ono, Koh

    2013-01-01

    MicroRNAs (miRs) are small non-protein-coding RNAs that bind to specific mRNAs and inhibit translation or promote mRNA degradation. Recent reports have indicated that miR-33, which is located within the intron of sterol regulatory element-binding protein (SREBP) 2, controls cholesterol homoeostasis and may be a potential therapeutic target for the treatment of atherosclerosis. Here we show that deletion of miR-33 results in marked worsening of high-fat diet-induced obesity and liver steatosis. Using miR-33−/−Srebf1+/− mice, we demonstrate that SREBP-1 is a target of miR-33 and that the mechanisms leading to obesity and liver steatosis in miR-33−/− mice involve enhanced expression of SREBP-1. These results elucidate a novel interaction between SREBP-1 and SREBP-2 mediated by miR-33 in vivo. PMID:24300912

  6. Comparison of Sterol Biomarkers for Sewage with other Measures in Victoria Harbour, B.C., Canada

    NASA Astrophysics Data System (ADS)

    Mudge, S. M.; Lintern, D. Gwyn

    1999-01-01

    A lipid biomarker survey was conducted in Victoria Harbour, Canada, to compare the distribution of sewage-derived organic matter with existing results from bacterial studies. Previous surveys [Miller (1993) Report prepared by Capital Regional District Engineering Department, Victoria, B.C. Canada and Miller et al. (1995) Report prepared by CRD Environmental Services Group and Aquatic Science Consultants Ltd., B.C., Canada] of sewage contamination in the harbour were based principally on infrequent faecal coliform counts. The use of lipid biomarkers to determine time-averaged concentrations of sewage components in sediments may be a more appropriate method for defining areas where sewage is causing environmental or human health risks. 5β-Coprostanol was measured together with other sterols, fatty acids and fatty alcohols. Generally, sewage contamination shown by these lipid biomarkers was coincident with high faecal coliform counts from previous studies. However, this survey suggests, contrary to faecal coliform counts, that Portage Inlet was a region where sewage had accumulated in the sediments, possibly due to nearby overflow facilities or tidal pumping. Although the bacterial counts were low, sewage-derived organic matter was accumulating in the slack areas. In sediments of the Gorge and West Bay there were low faecal biomarker concentrations; this was probably due to the strong tidal currents which do not allow faecal matter to settle in sediments. Faecal coliform counts, however, indicated poor water quality in these same regions but this probably reflects fresh discharges passing through this area without leading to settlement.

  7. Sterols from the red algae, Gracilaria salicornia and Hypnea flagelliformis, from Persian Gulf

    PubMed Central

    Nasir, Masoumeh; Saeidnia, Soodabeh; Mashinchian-Moradi, Ali; Gohari, Ahmad R.

    2011-01-01

    Context: Two of the important algae from Persian Gulf are Gracilaria salicornia and Hypnea flageliformis (Rhodophyta). Antibacterial, antifungal, and cytotoxic effects of the mentioned algae have been presented in the previous studies. Aim: In this study, the isolation and structural elucidation of the sterols from these algae are reported. Materials and Methods: The separation and purification of the compounds were carried out with silica gel, sephadex LH20 column chromatography (CC) and HPLC to obtain six pure compounds 1-6. The structural elucidation of the constituents was based on the data obtained from H-NMR,13C-NMR, HMBC, HSQC, DEPT, and EI-MS. Results: The isolated compounds from G. salicornia were identified as 22-dehydrocholesterol (1), cholesterol (2), oleic acid (3), and stigmasterol (4), and the isolated constituents from H. flagelliformis were identified as 22-dehydrocholesterol (1), cholesterol (2), oleic acid (3), cholesterol oleate (5), and (22E)-cholesta-5,22-dien-3β-ol-7-one (6) based on the spectral data compared to those reported in the literature. Conclusion: Red algae are enriched with cholesterol polysaccharides. We first reported the presence of cholesteryl oleate and (22E)-cholesta-5,22-dien-3β-ol-7-one in H. flagelliformis. PMID:21716930

  8. Fluconazole Binding and Sterol Demethylation in Three CYP51 Isoforms Indicate Differences in Active Site Topology

    SciTech Connect

    Bellamine, A.; Lepesheva, Galina I.; Waterman, Mike

    2010-11-16

    14{alpha}-Demethylase (CYP51) is a key enzyme in all sterol biosynthetic pathways (animals, fungi, plants, protists, and some bacteria), catalyzing the removal of the C-14 methyl group following cyclization of squalene. Based on mutations found in CYP51 genes from Candida albicans azole-resistant isolates obtained after fluconazole treatment of fungal infections, and using site-directed mutagenesis, we have found that fluconazole binding and substrate metabolism vary among three different CYP51 isoforms: human, fungal, and mycobacterial. In C. albicans, the Y132H mutant from isolates shows no effect on fluconazole binding, whereas the F145L mutant results in a 5-fold increase in its IC{sub 50} for fluconazole, suggesting that F145 (conserved only in fungal 14{alpha}-demethylases) interacts with this azole. In C. albicans, F145L accounts, in part, for the difference in fluconazole sensitivity reported between mammals and fungi, providing a basis for treatment of fungal infections. The C. albicans Y132H and human Y145H CYP51 mutants show essentially no effect on substrate metabolism, but the Mycobacterium tuberculosis F89H CYP51 mutant loses both its substrate binding and metabolism. Because these three residues align in the three isoforms, the results indicate that their active sites contain important structural differences, and further emphasize that fluconazole and substrate binding are uncoupled properties.

  9. Structure and Function of the Sterol Carrier Protein-2 N-Terminal Presequence†

    PubMed Central

    Martin, Gregory G.; Hostetler, Heather A.; McIntosh, Avery L.; Tichy, Shane E.; Williams, Brad J.; Russell, David H.; Berg, Jeremy M.; Spencer, Thomas A.; Ball, Judith; Kier, Ann B.; Schroeder, Friedhelm

    2008-01-01

    Although sterol carrier protein-2 (SCP-2) is encoded as a precursor protein (proSCP-2), little is known regarding the structure and function of the 20-amino acid N-terminal presequence. As shown herein, the presequence contains significant secondary structure and alters SCP-2: (i) secondary structure (CD), (ii) tertiary structure (aqueous exposure of Trp shown by UV absorbance, fluorescence, fluorescence quenching), (iii) ligand binding site [Trp response to ligands, peptide cross-linked by photoactivatable free cholesterol (FCBP)], (iv) selectivity for interaction with anionic phospholipid-rich membranes, (v) interaction with a peroxisomal import protein [FRET studies of Pex5p(C) binding], the N-terminal presequence increased SCP-2’s affinity for Pex5p(C) by 10-fold, and (vi) intracellular targeting in living and fixed cells (confocal microscopy). Nearly 5-fold more SCP-2 than proSCP-2 colocalized with plasma membrane lipid rafts/caveolae (AF488-CTB), 2.8-fold more SCP-2 than proSCP-2 colocalized with a mitochondrial marker (Mitotracker), but nearly 2-fold less SCP-2 than proSCP-2 colocalized with peroxisomes (AF488-antibody to PMP70). These data indicate the importance of the N-terminal presequence in regulating SCP-2 structure, cholesterol localization within the ligand binding site, membrane association, and, potentially, intracellular targeting. PMID:18465878

  10. Presence of methyl sterol and bacteriohopanepolyol in an outer-membrane preparation from Methylococcus capsulatus (Bath)

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda L.; Stan-Lotter, Helga; Kato, Katharine; Hochstein, Lawrence I.

    1992-01-01

    Cytoplasmic/intracytoplasmic and outer membrane preparations of Methylococcus capsulatus (Bath) were isolated by sucrose density gradient centrifugation of a total membrane fraction prepared by disruption using a French pressure cell. The cytoplasmic and/or intracytoplasmic membrane fraction consisted of two distinct bands, Ia and Ib (buoyant densities 1.16 and 1.18 g ml (exp -1), respectively) that together contained 57% of the protein, 68% of the phospholipid, 73% of the ubiquinone and 89% of the CN-sensitive NADH oxidase activity. The only apparent difference between these two cytoplasmic bands was a much higher phospholipid content for Ia. The outer membrane fraction (buoyant density 1.23-1.24 g ml (exp -1)) contained 60% of the lipopolysaccharide-associated, beta-hydroxypalmitic acid, 74% of the methylsterol, and 66% of the bacteriohopanepolyol (BHP); phospholipid to methyl sterol or BHP ratios were 6:1. Methanol dehydrogenase activity and a c-type cytochrome were also present in this outer membrane fraction. Phospholipase A activity was present in borh the cytoplasmic membrane and outer membrane fractions. The unique distribution of cyclic triterpenes may reflect a specific role in conferring outer membrane stability in this methanotrophic bacterium.

  11. Sterol Regulatory Element-Binding Protein-1c Regulates Inflammasome Activation in Gingival Fibroblasts Infected with High-Glucose-Treated Porphyromonas gingivalis

    PubMed Central

    Kuo, Hsing-Chun; Chang, Li-Ching; Chen, Te-Chuan; Lee, Ko-Chao; Lee, Kam-Fai; Chen, Cheng-Nan; Yu, Hong-Ren

    2016-01-01

    Background: Porphyromonas gingivalis is a major bacterial species implicated in the progression of periodontal disease, which is recognized as a common complication of diabetes. The interleukin (IL)-1β, processed by the NLR family pyrin domain containing 3 (NLRP3) inflammasome, has been identified as a target for pathogenic infection of the inflammatory response. However, the effect of P. gingivalis in a high-glucose situation in the modulation of inflammasome activation in human gingival fibroblasts (HGFs) is not well-understood. Methods: P. gingivalis strain CCUG25226 was used to study the mechanisms underlying the regulation of HGF NLRP3 expression by the infection of high-glucose-treated P. gingivalis (HGPg). Results: HGF infection with HGPg increases the expression of IL-1β and NLRP3. We further demonstrated that the upregulation of sterol regulatory element-binding protein (SREBP)-1c by activation of the Akt and p70S6K pathways is critical for HGPg-induced NLRP3 expression. We showed that the inhibition of Janus kinase 2 (JAK2) blocks the Akt- and p70S6K-mediated SREBP-1c, NLRP3, and IL-1β expression. The effect of HGPg on HGF signaling and NLRP3 expression is mediated by β1 integrin. In addition, gingival tissues from diabetic patients with periodontal disease exhibited higher NLRP3 and SREBP-1c expression. Conclusions: Our findings identify the molecular pathways underlying HGPg-dependent NLRP3 inflammasome expression in HGFs, providing insight into the effect of P. gingivalis invasion in HGFs. PMID:28083517

  12. The role of Niemann-Pick C1 - Like 1 (NPC1L1) in intestinal sterol absorption.

    PubMed

    Turley, Stephen D

    2008-04-01

    The absorption of cholesterol by the proximal small intestine represents a major pathway for the entry of cholesterol into the body pools. This cholesterol is derived primarily from the bile and the diet. In adult humans, typically several hundred milligrams of cholesterol reach the liver from the intestine daily, with the potential to impact the plasma low density lipoprotein-cholesterol (LDL-C) concentration. There are three main phases involved in cholesterol absorption. The first occurs intraluminally and culminates in micellar solubilization of unesterified cholesterol which facilitates its movement up to the brush border membrane (BBM) of the enterocyte. The second phase involves the transport of cholesterol across the BBM by Niemann-Pick C1 Like-1 (NPC1L1), while the third phase entails a series of steps within the enterocyte involving the esterification of cholesterol and its incorporation, along with other lipids and apolipoprotein B48 (apo B48), into nascent chylomicrons (CM). The discovery of the role of NPC1L1 in intestinal sterol transport occurred directly as a consequence of efforts to identify the molecular target of ezetimibe, a novel, potent, and specific inhibitor of sterol absorption that is now widely used in combination therapy with statins for the management of hypercholesterolemia in the general population. Some aspects of the role of NPC1L1 in cholesterol absorption nevertheless remain controversial and are the subject of ongoing research. For example, one report suggests that NPC1L1 is located not in the plasma membrane but intracellularly where it is thought to be involved in cytosolic trafficking of cholesterol, while another concludes that a protein other than NPC1L1 is responsible for the high affinity binding of cholesterol on intestinal BBM. However, other new studies which show that the in vivo responsiveness of different species to ezetimibe correlates with NPC1L1 binding affinity further support the widely held belief that NPC1L1

  13. Inhibition of cholesterol synthesis ex vivo and in vivo by fluvastatin, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase.

    PubMed

    Yamamoto, A; Itoh, S; Hoshi, K; Ichihara, K

    1995-03-15

    The inhibitory effect of fluvastatin sodium (fluvastatin), a new type of 3-hydroxy-3-methylglutaryl (HMG) coenzyme A inhibitor, on de novo cholesterol synthesis was investigated and compared with that of pravastatin. Fluvastatin at a concentration of 12.5 mg/kg inhibited sterol synthesis ex vivo from [14C]acetate in rat liver and ileum by 97-99% with respect to the control, while the inhibition in kidney was 55%. The inhibition by fluvastatin in the liver and ileum persisted for approximately 9 h after administration. Significant differences between fluvastatin also had an inhibitory effect on cholesterol synthesis in vivo in various tissues of rats given [14C]acetate intraperitoneally. Sterol synthesis in the liver, ileum and kidney was inhibited by over 95% 3 h after administration of 6.25 mg/kg of fluvastatin. Significant differences between fluvastatin and pravastatin were found in the liver and ileum. Fluvastatin was more potent than pravastatin in inhibiting both ex vivo and in vivo sterol synthesis in the ileum (but not in kidney) and liver.

  14. The effects of cell death-inducing DNA fragmentation factor-α-like effector C on milk lipid synthesis in mammary glands of dairy cows.

    PubMed

    Yang, Yang; Lin, Ye; Duan, Xiaoyu; Lv, He; Xing, Weinan; Li, Qingzhang; Gao, Xuejun; Hou, Xiaoming

    2017-03-08

    Adequate lipid synthesis by the mammary gland during lactation is essential for the survival of mammalian offspring. Cell death-inducing DNA fragmentation factor-α-like effector C (CIDEC) is a lipid droplet-associated protein and functions to promote lipid accumulation and inhibit lipolysis in mice and human adipocytes. However, the function of CIDEC in regulation of milk lipid synthesis in dairy cow mammary gland remains largely unknown. In this study, 6 multiparous Holstein cows (parity = 3) in early lactation were allocated to high-fat milk (milk yield 33.9 ± 2.1 kg/d, milk fat >3.5%, n = 3) and low-fat milk (milk yield 33.7 ± 0.5 kg/d, milk fat <3.5%, n = 3) groups according to their milk fat content. Lactating cows were slaughtered at 90 d in milk and mammary tissues were collected to detect CIDEC localization. Immunofluorescence staining of sections of lactating mammary glands with high- and low-fat milk showed that CIDEC was expressed in the cytoplasm of epithelial cells and localized to lipid droplets. Lipid droplets and CIDEC protein were also detected in isolated lactating mammary epithelial cells of dairy cows. Immunostaining of CIDEC in isolated mammary epithelial cells also confirmed its presence in the nucleus. The knockdown of CIDEC in cultured bovine mammary epithelial cells decreased milk lipid content and reduced expression of genes associated with mammary de novo fatty acid synthesis, short- and long-chain intracellular fatty acid activation, triacylglycerol synthesis, and transcription regulation. These genes included those for acetyl-CoA carboxylase (ACC, -60%), fatty acid synthase (FASN, -65%), acyl-CoA synthetase short-chain family member 2 (ACSS2, -50%), acyl-CoA synthetase long-chain family member 1 (ACSL1, -30%), diacylglycerol acyltransferase 1 (DGAT1, -60%), sterol regulatory element-binding protein 1 (SREBP1, -45%), and SREBP cleavage activating protein (SCAP, -66%). Conversely, in cells overexpressing CIDEC, triacylglycerol content

  15. Aloe sterol supplementation improves skin elasticity in Japanese men with sunlight-exposed skin: a 12-week double-blind, randomized controlled trial

    PubMed Central

    Tanaka, Miyuki; Yamamoto, Yuki; Misawa, Eriko; Nabeshima, Kazumi; Saito, Marie; Yamauchi, Koji; Abe, Fumiaki; Furukawa, Fukumi

    2016-01-01

    Background/objective Recently, it was confirmed that the daily oral intake of plant sterols of Aloe vera gel (Aloe sterol) significantly increases the skin barrier function, moisture, and elasticity in photoprotected skin. This study aimed to investigate whether Aloe sterol intake affected skin conditions following sunlight exposure in Japanese men. Methods We performed a 12-week, randomized, double-blind, placebo-controlled study to evaluate the effects of oral Aloe sterol supplementation on skin conditions in 48 apparently healthy men (age range: 30–59 years; average: 45 years). The subjects were instructed to expose the measurement position of the arms to the sunlight outdoors every day for 12 weeks. The skin parameters were measured at 0 (baseline), 4, 8, and 12 weeks. Results Depending on the time for the revelation of the sunlight, the b* value and melanin index increased and the skin moisture decreased. After taking an Aloe sterol tablet daily for 12 weeks, the skin elasticity index (R2, R5, and R7) levels were significantly higher than the baseline value. There were no differences between the groups in these skin elasticity values. In the subgroup analysis of subjects aged <46 years, the change in the R5 and R7 was significantly higher in the Aloe group than in the placebo group at 8 weeks (P=0.0412 and P=0.0410, respectively). There was a difference in the quantity of sun exposure between each subject, and an additional clinical study that standardizes the amount of ultraviolet rays is warranted. No Aloe sterol intake-dependent harmful phenomenon was observed during the intake period. Conclusion Aloe sterol ingestion increased skin elasticity in the photodamaged skin of men aged <46 years. PMID:27877061

  16. LDL-cholesterol-lowering effect of plant sterols and stanols across different dose ranges: a meta-analysis of randomised controlled studies.

    PubMed

    Ras, Rouyanne T; Geleijnse, Johanna M; Trautwein, Elke A

    2014-07-28

    Phytosterols (PS, comprising plant sterols and plant stanols) have been proven to lower LDL-cholesterol concentrations. The dose-response relationship for this effect has been evaluated in several meta-analyses by calculating averages for different dose ranges or by applying continuous dose-response functions. Both approaches have advantages and disadvantages. So far, the calculation of averages for different dose ranges has not been done for plant sterols and stanols separately. The objective of the present meta-analysis was to investigate the combined and separate effects of plant sterols and stanols when classified into different dose ranges. Studies were searched and selected based on predefined criteria. Relevant data were extracted. Average LDL-cholesterol effects were calculated when studies were categorised by dose, according to random-effects models while using the variance as weighing factor. This was done for plant sterols and stanols combined and separately. In total, 124 studies (201 strata) were included. Plant sterols and stanols were administered in 129 and fifty-nine strata, respectively; the remaining used a mix of both. The average PS dose was 2.1 (range 0.2-9.0) g/d. PS intakes of 0.6-3.3 g/d were found to gradually reduce LDL-cholesterol concentrations by, on average, 6-12%. When plant sterols and stanols were analysed separately, clear and comparable dose-response relationships were observed. Studies carried out with PS doses exceeding 4 g/d were not pooled, as these were scarce and scattered across a wide range of doses. In conclusion, the LDL-cholesterol-lowering effect of both plant sterols and stanols continues to increase up to intakes of approximately 3 g/d to an average effect of 12%.

  17. Regulation of cholesterol synthesis in four colonic adenocarcinoma cell lines.

    PubMed

    Cerda, S R; Wilkinson, J; Broitman, S A

    1995-12-01

    Colon tumor cells, unlike normal human fibroblasts, exhibited an uncoupling of low density lipoprotein (LDL)-derived cholesterol from cellular growth, when endogenous cholesterol synthesis was inhibited by mevinolin, a hydroxymethylglutaryl-CoA reductase (HMG-CoAR) competitive inhibitor [Fabricant, M., and Broitman, S.A. (1990) Cancer Res. 50, 632-636]. Further evaluation of cholesterol metabolism was conducted in two undifferentiated (SW480, SW1417) and two differentiated (HT29, CACO2) colonic adenocarcinoma (adeno-CA) cell lines and an untransformed human fibroblast, AG1519A. Cells grown in monolayer culture to near subconfluency were used to assess endogenous cholesterol synthesis by 14C-acetate incorporation, in response to the following treatments in lipoprotein-deficient serum (LPDS)-supplemented minimum essential medium (MEM): LPDS alone, LDL, mevinolin, mevinolin with LDL, and 25-hydroxy-cholesterol (25-OH-CH). Complete fetal bovine serum (FBS)-supplemented MEM was used as control. All colon tumor lines exhibited similarly high endogenous cholesterol synthesis in both FBS and LPDS relative to the fibroblasts which demonstrated low basal levels in FBS and maximal synthesis in LPDS. LDL treatment did not inhibit cholesterol synthesis in colon tumor cells, but suppressed that in the fibroblast by 70%. Sterol repression of cholesterol synthesis mediated by 25-OH-CH occurred in all cells. Mevinolin caused a reduction in cholesterol synthesis in the colonic cancer cell lines, which was not further decreased by concurrent addition of LDL. In contrast, in mevinolin-treated fibroblasts, LDL further inhibited cholesterol synthesis. When the effect of cell density on cholesterol synthesis regulation was evaluated under conditions of sparse density in SW480 and SW147, results indicated that (i) basal rates of cholesterol synthesis were higher, (ii) LDL inhibited cholesterol synthesis more effectively, and (iii) mevinolin or 25-OH-CH had a more pronounced effect than in

  18. Sterol-Modified Phospholipids: Cholesterol and Phospholipid Chimeras with Improved Biomembrane Properties

    PubMed Central

    Huang, Zhaohua; Szoka, Francis C.

    2009-01-01

    We synthesized a family of sterol-modified glycerophospholipids (SML) in which the sn-1 or sn-2 position is covalently attached to cholesterol and the alternative position contains an aliphatic chain. The SML were used to explore how anchoring cholesterol to a phospholipid affects cholesterol behavior in a bilayer. Notably, cholesterol in the SML retains the membrane condensing properties of free cholesterol regardless of the chemistry or position of its attachment to the glycerol moiety of the phospholipid. SMLs by themselves formed liposomes upon hydration and in mixtures between an SML and diacylglycerophospholipids (C14 to C18 chain length) the thermotropic phase transition is eliminated at the SML equivalent of about 30 mole percent free cholesterol. Osmotic-induced contents leakage from SML (C14–C18) liposomes depends upon the linkage and position of cholesterol but in general is similar to that observed in diacylphosphatidylcholine/ cholesterol: 3/2 (mole ratio) liposomes. SML liposomes are exceptionally resistant to contents release in the presence of serum at 37 °C. This is probably due to fact that SML exchange between bilayers is more than 100 fold less than the exchange rate of free cholesterol in the same conditions. Importantly SML liposomes containing doxorubicin are as effective in treating the murine C26 colon carcinoma, as Doxil™ a commercial liposome doxorubicin formulation. SMLs stabilize bilayers but do not exchange hence provide a new tool for biophysical studies on membranes and they may improve liposomal drug delivery in organs predisposed to the extraction of free cholesterol from bilayers, such as; the skin, lung or blood. PMID:18950160

  19. Oral Delivery of a Synthetic Sterol Reduces Axonopathy and Inflammation in a Rodent Model of Glaucoma.

    PubMed

    Lambert, Wendi S; Carlson, Brian J; Formichella, Cathryn R; Sappington, Rebecca M; Ahlem, Clarence; Calkins, David J

    2017-01-01

    Glaucoma is a group of optic neuropathies associated with aging and sensitivity to intraocular pressure (IOP). The disease is the leading cause of irreversible blindness worldwide. Early progression in glaucoma involves dysfunction of retinal ganglion cell (RGC) axons, which comprise the optic nerve. Deficits in anterograde transport along RGC axons to central visual structures precede outright degeneration, and preventing these deficits is efficacious at abating subsequent progression. HE3286 is a synthetic sterol derivative that has shown therapeutic promise in models of inflammatory disease and neurodegenerative disease. We examined the efficacy of HE3286 oral delivery in preventing loss of anterograde transport in an inducible model of glaucoma (microbead occlusion). Adult rats received HE3286 (20 or 100 mg/kg) or vehicle daily via oral gavage for 4 weeks. Microbead occlusion elevated IOP ~30% in all treatment groups, and elevation was not affected by HE3286 treatment. In the vehicle group, elevated IOP reduced anterograde axonal transport to the superior colliculus, the most distal site in the optic projection, by 43% (p = 0.003); HE3286 (100 mg/kg) prevented this reduction (p = 0.025). HE3286 increased brain-derived neurotrophic factor (BDNF) in the optic nerve head and retina, while decreasing inflammatory and pathogenic proteins associated with elevated IOP compared to vehicle treatment. Treatment with HE3286 also increased nuclear localization of the transcription factor NFκB in collicular and retinal neurons, but decreased NFκB in glial nuclei in the optic nerve head. Thus, HE3286 may have a neuroprotective influence in glaucoma, as well as other chronic neurodegenerations.

  20. Comparison of bile salt/phosphatidylcholine mixed micelles in solubilization to sterols and stability

    PubMed Central

    Guo, Qin; Cai, Jie; Li, Pengyu; Xu, Dongling; Ni, Xiaomin; Wen, Hui; Liu, Dan; Lin, Suizhen; Hu, Haiyan

    2016-01-01

    Androst-3β,5α,6β-triol (Triol) is a promising neuroprotective agent, but its poor solubility restricts its development into parenteral preparations. In this study, Triol is significantly solubilized by bile salt/phosphatidylcholine mixed micelles (BS/PC-MM). All BS/PC-MM systems are tested to remarkably improve the drug solubility with various stabilities after drug loading. Among them, the sodium glycocholate (SGC)/egg phosphatidylcholine (EPC) system with 2:1 ratio in weight and the total concentration of SGC and EPC of 100 mg/mL is proved to produce stable mixed micelles with high drug loading. It is found that the stability of drug-loaded mixed micelles is quite different, which might be related to the change in critical micelle concentration (CMC) after incorporating drugs. SGC/EPC and SGC/soya phosphatidylcholine (SPC) remain transparent under accelerated conditions and manifest a decreased CMC (dropping from 0.105 to 0.056 mg/mL and from 0.067 to 0.024 mg/mL, respectively). In contrast, swine bile acid-sodium salt (SBA-Na)/PC and sodium deoxycholate (SDC)/PC are accompanied by drug precipitation and reached the maximum CMC on the first and the third days, respectively. Interestingly, the variation of CMC under accelerated testing conditions highly matches the drug-precipitating event in the primary stability experiment. In brief, the bile salt/phosphatidylcholine system exists as a potential strategy of improving sterol drug solubility. CMC variation under accelerated testing conditions might be a simple and easy method to predict the stability of drug-loaded mixed micelles. PMID:27895469

  1. Prevention of Endotoxin-Induced Uveitis in Rats by Plant Sterol Guggulsterone

    PubMed Central

    Kalariya, Nilesh M.; Shoeb, Mohammad; Reddy, Aramati B. M.; Zhang, Min; van Kuijk, Frederik J. G. M.

    2010-01-01

    Purpose. To investigate the anti-inflammatory effects of guggulsterone, an antioxidant and antitumor agent, in endotoxin-induced uveitis (EIU) in rats and to elucidate the underlying molecular mechanism or mechanisms related to ocular inflammation. Methods. EIU was induced by subcutaneous injection of lipopolysaccharide (LPS; 150 μg) into Lewis rats treated with guggulsterone (30 mg/kg body weight, intraperitoneally) or its carrier. After 24 hours the rats were killed, eyes were enucleated, and aqueous humor (AqH) was collected. Numbers of infiltrating cells and levels of matrix metalloproteinase-2 (MMP-2), nitric oxide (NO), and prostaglandin E2 (PGE2) were determined in AqH by specific ELISAs. An antibody array was used to measure the expression of various inflammatory cytokines in AqH. The expression of MMP-2, iNOS, Cox-2, phospho-IκB, and phospho-NF-κB was determined immunohistochemically. Human primary nonpigment ciliary epithelial cells (HNPECs) were used to determine the in vitro efficacy of guggulsterone on the LPS-induced inflammatory response. Results. Compared with control, the EIU rat eye AqH had a significantly higher number of infiltrating cells, total protein, and inflammatory markers, such as MMP-2, NO, and PGE2, and the treatment of guggulsterone prevented EIU-induced increases. Guggulsterone also prevented the expression of MMP-2, iNOS, and Cox-2 proteins and of IκB and NF-κB in various eye tissues. Moreover, in cultured HNPECs, guggulsterone inhibited LPS-induced expression of inflammatory proteins. Conclusions. These results for the first time demonstrate that the plant sterol guggulsterone suppresses ocular inflammation in EIU, suggesting that the supplementation of guggulsterone could be a novel approach for the treatment of ocular inflammation. PMID:20435582

  2. Oral Delivery of a Synthetic Sterol Reduces Axonopathy and Inflammation in a Rodent Model of Glaucoma

    PubMed Central

    Lambert, Wendi S.; Carlson, Brian J.; Formichella, Cathryn R.; Sappington, Rebecca M.; Ahlem, Clarence; Calkins, David J.

    2017-01-01

    Glaucoma is a group of optic neuropathies associated with aging and sensitivity to intraocular pressure (IOP). The disease is the leading cause of irreversible blindness worldwide. Early progression in glaucoma involves dysfunction of retinal ganglion cell (RGC) axons, which comprise the optic nerve. Deficits in anterograde transport along RGC axons to central visual structures precede outright degeneration, and preventing these deficits is efficacious at abating subsequent progression. HE3286 is a synthetic sterol derivative that has shown therapeutic promise in models of inflammatory disease and neurodegenerative disease. We examined the efficacy of HE3286 oral delivery in preventing loss of anterograde transport in an inducible model of glaucoma (microbead occlusion). Adult rats received HE3286 (20 or 100 mg/kg) or vehicle daily via oral gavage for 4 weeks. Microbead occlusion elevated IOP ~30% in all treatment groups, and elevation was not affected by HE3286 treatment. In the vehicle group, elevated IOP reduced anterograde axonal transport to the superior colliculus, the most distal site in the optic projection, by 43% (p = 0.003); HE3286 (100 mg/kg) prevented this reduction (p = 0.025). HE3286 increased brain-derived neurotrophic factor (BDNF) in the optic nerve head and retina, while decreasing inflammatory and pathogenic proteins associated with elevated IOP compared to vehicle treatment. Treatment with HE3286 also increased nuclear localization of the transcription factor NFκB in collicular and retinal neurons, but decreased NFκB in glial nuclei in the optic nerve head. Thus, HE3286 may have a neuroprotective influence in glaucoma, as well as other chronic neurodegenerations. PMID:28223915

  3. Effects of Dietary Plant Sterols and Stanol Esters with Low- and High-Fat Diets in Chronic and Acute Models for Experimental Colitis.

    PubMed

    te Velde, Anje A; Brüll, Florence; Heinsbroek, Sigrid E M; Meijer, Sybren L; Lütjohann, Dieter; Vreugdenhil, Anita; Plat, Jogchum

    2015-10-15

    In this study, we evaluated the effects of dietary plant sterols and stanols as their fatty acid esters on the development of experimental colitis. The effects were studied both in high- and low-fat diet conditions in two models, one acute and another chronic model of experimental colitis that resembles gene expression in human inflammatory bowel disease (IBD). In the first experiments in the high fat diet (HFD), we did not observe a beneficial effect of the addition of plant sterols and stanols on the development of acute dextran sulphate sodium (DSS) colitis. In the chronic CD4CD45RB T cell transfer colitis model, we mainly observed an effect of the presence of high fat on the development of colitis. In this HFD condition, the presence of plant sterol or stanol did not result in any additional effect. In the second experiments with low fat, we could clearly observe a beneficial effect of the addition of plant sterols on colitis parameters in the T cell transfer model, but not in the DSS model. This positive effect was related to the gender of the mice and on Treg presence in the colon. This suggests that especially dietary plant sterol esters may improve intestinal inflammation in a T cell dependent manner.

  4. Crystal Structures of Trypanosoma brucei Sterol 14[alpha]-Demethylase and Implications for Selective Treatment of Human Infections

    SciTech Connect

    Lepesheva, Galina I.; Park, Hee-Won; Hargrove, Tatiana Y.; Vanhollebeke, Benoit; Wawrzak, Zdzislaw; Harp, Joel M.; Sundaramoorthy, Munirathinam; Nes, W. David; Pays, Etienne; Chaudhuri, Minu; Villalta, Fernando; Waterman, Michael R.

    2010-01-25

    Sterol 14{alpha}-demethylase (14DM, the CYP51 family of cytochrome P450) is an essential enzyme in sterol biosynthesis in eukaryotes. It serves as a major drug target for fungal diseases and can potentially become a target for treatment of human infections with protozoa. Here we present 1.9 {angstrom} resolution crystal structures of 14DM from the protozoan pathogen Trypanosoma brucei, ligand-free and complexed with a strong chemically selected inhibitor N-1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethyl-4-(5-phenyl-1,3,4-oxadi-azol-2-yl)benzamide that we previously found to produce potent antiparasitic effects in Trypanosomatidae. This is the first structure of a eukaryotic microsomal 14DM that acts on sterol biosynthesis, and it differs profoundly from that of the water-soluble CYP51 family member from Mycobacterium tuberculosis, both in organization of the active site cavity and in the substrate access channel location. Inhibitor binding does not cause large scale conformational rearrangements, yet induces unanticipated local alterations in the active site, including formation of a hydrogen bond network that connects, via the inhibitor amide group fragment, two remote functionally essential protein segments and alters the heme environment. The inhibitor binding mode provides a possible explanation for both its functionally irreversible effect on the enzyme activity and its selectivity toward the 14DM from human pathogens versus the human 14DM ortholog. The structures shed new light on 14DM functional conservation and open an excellent opportunity for directed design of novel antiparasitic drugs.

  5. Effect of low-fat, high-carbohydrate, high-fiber diet on fecal bile acids and neutral sterols.

    PubMed

    Reddy, B S; Engle, A; Simi, B; O'Brien, L T; Barnard, R J; Pritikin, N; Wynder, E L

    1988-07-01

    The effect of a diet low in total fat and high in complex carbohydrates on the excretion of bile acids and neutral sterols and on serum lipids was studied in women, 46-47 years old, who were consuming a mixed Western diet. Participants kept an initial 3-day food record while consuming their normal diet (pre-diet period). During the dietary intervention period (experimental diet) which lasted for 26 days, all volunteers consumed a low-calorie, low-fat (less than 10% of total calories), high-fiber (37 g/day, high-carbohydrate diet. At the 1-year follow-up, the participants completed another 3-day food record, which indicates that these volunteers maintained their caloric and fat intake at levels slightly higher than the experimental diet, but lower than the pre-diet period. Individual 24-hr fecal samples for 2 days and blood samples were collected from the volunteers during each dietary period. Fecal samples were analyzed for neutral sterols and bile acids, and blood samples were analyzed to ascertain cholesterol and triglyceride levels. There were no significant differences in the excretion of neutral sterols between the dietary periods. Fecal secondary bile acids were significantly lower during the experimental and follow-up diet periods compared with the pre-test diet period. Serum cholesterol levels were significantly lower during the experimental and follow-up diet periods than during the pre-test diet period. These results suggest that switching from a high-fat, low-fiber diet to a low-fat, high-fiber diet can reduce the excretion of bile acids which are thought to be involved in the promotion of colon cancer.

  6. Effects of Mutations in Aedes aegypti Sterol Carrier Protein-2 on the Biological Function of the Protein

    PubMed Central

    Radek, James T.; Dyer, David H.; Lan, Que

    2010-01-01

    Sterol carrier protein-2 (SCP-2) is a non-specific intracellular lipid carrier protein. However, the molecular mechanism of ligand selectivity and the in vivo function of SCP-2 remain unclear. In this study, we used site directed mutagenesis to investigate ligand selectivity and in vivo function of the yellow fever mosquito sterol carrier protein-2 protein (AeSCP-2). Mutations to amino acids in AeSCP-2 known to interact with bound ligand also decreased NBD-cholesterol binding. Substitution of amino acids in the ligand cavity changed the ligand specificity of mutant AeSCP-2. Over-expressing AeSCP-2 wild-type in the Aedes aegypti cultured Aag-2 cells resulted in an increase in incorporation of [3H]cholesterol. However, over-expressing mutants that were deleterious to the binding of NBD-cholesterol in AeSCP-2 showed a loss in the ability to enhance uptake of [3H] cholesterol in cultured cells. Interestingly, when [3H]palmitic acid was used as the substrate for incorporation in vivo, there was no change in the levels of incorporation with over-expression of wild-type protein or mutated AeSCP-2s. The in vivo data suggest that AeSCP-2 is involved in sterol uptake, but not fatty acid uptake. This is the first report that the ability of cholesterol binding may directly correlate to AeSCP-2’s in vivo function in aiding the uptake of cholesterol. PMID:20681612

  7. Low concentrations of the non-ionic detergent Nonidet P-40 interfere with sterol biogenesis and viability of the yeast Saccharomyces cerevisiae.

    PubM