Effects of Free Sterols, Steryl Ester, and Steryl Glycoside on Membrane Permeability

C. Grunwald

doi:10.1104/pp.48.5.653

The free sterol, steryl ester, and steryl glycoside content of tomato cultivars resistant and susceptible to Phytophthora infestans

Canadian Journal of Botany ◽

10.1139/b82-187 ◽

1982 ◽

Vol 60 (8) ◽

pp. 1469-1473 ◽

Cited By ~ 2

Author(s):

B. Bradford ◽

L. D. Moore ◽

D. M. Orcutt

Keyword(s):

Late Blight ◽

Free Sterol ◽

Steryl Ester ◽

Total Sterol ◽

Dry Weight ◽

The Other ◽

Sterol Content ◽

New Yorker ◽

Steryl Glycoside ◽

Tomato Cultivars

Leaf sterols were extracted from three late blight resistant ('Nova,' 'New Yorker,' and 'West Virginia 63') and three late blight susceptible ('Beefsteak,' 'Jubilee,' and 'San Marzano') cultivars of tomato (Lycopersicon esculentum Mill.). There were no significant differences (P < 0.05), either quantitatively or qualitatively, between the sterol contents of the resistant and the susceptible cultivars. Of the six cultivars only the steryl glycoside class of 'San Marzano' was significantly higher than that of the other cultivars. The total sterol content was 2.95–3.84 mg/g dry weight and was composed of 23–32% free sterol, 4–6% steryl ester, and 63–71% steryl glycoside. The relative susceptibility of tomato to late blight is not related to the free sterol or conjugated forms of sterols in the plant.

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The Saccharomyces cerevisiae YLL012/YEH1, YLR020/YEH2, and TGL1 Genes Encode a Novel Family of Membrane-Anchored Lipases That Are Required for Steryl Ester Hydrolysis

Molecular and Cellular Biology ◽

10.1128/mcb.25.5.1655-1668.2005 ◽

2005 ◽

Vol 25 (5) ◽

pp. 1655-1668 ◽

Cited By ~ 95

Author(s):

René Köffel ◽

Rashi Tiwari ◽

Laurent Falquet ◽

Roger Schneiter

Keyword(s):

Saccharomyces Cerevisiae ◽

Steryl Ester ◽

Ester Hydrolysis ◽

Open Reading Frames ◽

Yeast Cells ◽

Acid Lipase ◽

Triple Mutant ◽

Free Sterols ◽

Steryl Esters

ABSTRACT Sterol homeostasis in eukaryotic cells relies on the reciprocal interconversion of free sterols and steryl esters. The formation of steryl esters is well characterized, but the mechanisms that control steryl ester mobilization upon cellular demand are less well understood. We have identified a family of three lipases of Saccharomyces cerevisiae that are required for efficient steryl ester mobilization. These lipases, encoded by YLL012/YEH1, YLR020/YEH2, and TGL1, are paralogues of the mammalian acid lipase family, which is composed of the lysosomal acid lipase, the gastric lipase, and four novel as yet uncharacterized human open reading frames. Lipase triple-mutant yeast cells are completely blocked in steryl ester hydrolysis but do not affect the mobilization of triacylglycerols, indicating that the three lipases are required for steryl ester mobilization in vivo. Lipase single mutants mobilize steryl esters to various degrees, indicating partial functional redundancy of the three gene products. Lipase double-mutant cells in which the third lipase is expressed from the inducible GAL1 promoter have greatly reduced steady-state levels of steryl esters, indicating that overexpression of any of the three lipases is sufficient for steryl ester mobilization in vivo. The three yeast enzymes constitute a novel class of membrane-anchored lipases that differ in topology and subcellular localization.

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Initial Polymerization Sites Indicated During Mitochondrial Oxidation of Diaminobenzidine after Toluene Treatment

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079498 ◽

1977 ◽

Vol 35 ◽

pp. 408-409

Author(s):

W. A. Shannon ◽

M. A. Matlib

Keyword(s):

Membrane Permeability ◽

Cytochrome Oxidase ◽

Rat Liver ◽

Precise Definition ◽

Cytochemical Localization ◽

Oxidative Reaction ◽

Mitochondrial Oxidation ◽

Definition Of ◽

Exogenous Substrates

Numerous studies have dealt with the cytochemical localization of cytochrome oxidase via cytochrome c. More recent studies have dealt with indicating initial foci of this reaction by altering incubation pH (1) or postosmication procedure (2,3). The following study is an attempt to locate such foci by altering membrane permeability. It is thought that such alterations within the limits of maintaining morphological integrity of the membranes will ease the entry of exogenous substrates resulting in a much quicker oxidation and subsequently a more precise definition of the oxidative reaction.The diaminobenzidine (DAB) method of Seligman et al. (4) was used. Minced pieces of rat liver were incubated for 1 hr following toluene treatment (5,6). Experimental variations consisted of incubating fixed or unfixed tissues treated with toluene and unfixed tissues treated with toluene and subsequently fixed.

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Sarcolemmal permeability changes during early myocardial anoxia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084089 ◽

1978 ◽

Vol 36 (2) ◽

pp. 642-643

Author(s):

M. Ashraf ◽

L. Landa ◽

L. Nimmo ◽

C. M. Bloor

Keyword(s):

Cell Membrane ◽

Membrane Permeability ◽

Coronary Artery Occlusion ◽

Artery Occlusion ◽

Cell Membrane Permeability ◽

Enzyme Release ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Sarcolemmal Permeability ◽

Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

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