Document Detail


Effect of sterol replacement in vivo on the fatty acid composition of Tetrahymena.
MedLine Citation:
PMID:  808549     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The addition of ergosterol to cultures of Tetrahymena pyriformis results in (a) the accumulation of the sterol by the cells; (b) the inhibition of the synthesis of the pentacyclic triterpenoid alcohol, tetrahymanol; (c) the replacement of tetrahymanol by ergosterol in the ciliate membranes. The dry weight and lipid content of sterol-supplemented ciliates did not differ from the controls. Examination of the lipid classes revealed no change in composition except for a higher content of ergosterol in supplemented cells than tetrahymanol in control cultures. The relative proportions of triglycerides, the major classes of polar lipids, 1-alkyl phospholipids and phosphonolipids, appeared unaltered. A complex array of fatty acids is found in this ciliate. Several acids not reported previously in this organism were isolated and identified, and the novel fatty acid 18:2 delta 6, 11, was found in substantial amounts. Ergosterol supplementation altered the proportions of the fatty acids, although not all lipid classes were affected to the same extent. The changes noted were of three general types: (a) a shortening of the fatty acyl chain length in the acids of the normal series; (b) a lowering in the degree of unsaturation; (c) a discrimination between two isomers of lionoleate, 18:2 delta 6, 11 and 18:2 delta 9, 12. The former is elevated in the presence of ergosterol while the latter is depressed. Each class of polar lipids has a distinctive fatty acid composition. Among the glycerophospholipids, cardiolipin and phosphatidylcholine were least affected, while the mixture of 1-alkyl-2-acyl-sn-glycero-3-(2-aminoethyl)-phosphonate and 1,2-diacyl-sn-glycero-3-(2-aminoethyl)-phosphonate was most markedly altered. Sphingolipid fatty acid composition was influenced by ergosterol supplementation. Two changes were noted: (a) a reduction in the length of the hydrocarbon chain; (b) an increase in the proportion of alpha-hydroxy acids. The impact of ergosterol on the fatty acid composition of the polar lipids may be on fatty acid biosynthesis, on incorporation of fatty acids, or on the turnover rates of the fatty acyl groups. Ergosterol is concentrated in the ciliary (limiting) membrane, as are the polar lipids most affected. This localization allows the speculation that the change in fatty acid composition may be related to the maintenance of optimal membrane properties upon the introduction of the sterol.
Authors:
K A Ferguson; F M Davis; R L Conner; J R Landrey; F B Mallory
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  250     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1975 Sep 
Date Detail:
Created Date:  1975-12-04     Completed Date:  1975-12-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  6998-7005     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Ergosterol / metabolism*,  pharmacology
Fatty Acids / analysis,  metabolism*
Fatty Acids, Unsaturated / analysis,  biosynthesis
Phospholipids / analysis,  biosynthesis
Tetrahymena pyriformis / analysis,  drug effects,  metabolism*
Chemical
Reg. No./Substance:
0/Fatty Acids; 0/Fatty Acids, Unsaturated; 0/Phospholipids; 57-87-4/Ergosterol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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