Document Detail

Phosphatidylcholine formation is the predominant lipid biosynthetic event in the hemoparasite Babesia bovis.
MedLine Citation:
PMID:  10743618     Owner:  NLM     Status:  MEDLINE    
This work examines the lipid composition and metabolism of bovine red blood cells infected by apicomplexan Babesia parasites, organisms closely related to Plasmodium sp. We found that erythrocytes infected with Babesia bovis (i-RBC) accumulate lipids and show striking increases in phosphatidylcholine, phosphatidic acid, diacylglycerol and cholesteryl esters as compared to uninfected erythrocytes cultured under the same conditions (n-RBC). A similar pattern was observed in cultures of erythrocytes infected with Babesia bigemina. The lipid profile of purified B. bovis merozoites showed that phosphatidylcholine is the most abundant phospholipid in this parasite (31.8% +/- 2.8 of total phospholipid), markedly differing from bovine n-RBC, in which it is only a minor component (4.8% +/- 0.6). B. bovis cultures incorporate radiolabeled choline into complex lipids, especially phosphatidylcholine, with minor amounts recovered in sphingomyelin and lysophosphatidylcholine. When [14C] stearate was used as precursor, the labeling pattern again gave the highest incorporation into phosphatidylcholine, with lesser incorporation in sphingomyelin, phosphatidylinositol, phosphatidylethanolamine and phosphatidic acid. Diacylglycerol and small amounts of cholesteryl esters were the only labeled neutral lipids found. B. bovis also incorporates [3H] myo-inositol into phosphatidylinositol. Parallel incubations with n-RBC as a control yielded no incorporation into either polar or neutral lipids with any precursor. These results indicate that the lipid changes observed in i-RBC can be explained on the basis of the lipid biosynthetic activities of the babesial parasite. Gas chromatography-mass spectrometry (GC-MS) analysis of fatty acid methyl esters from phospholipids of i-RBC and n-RBC showed the same qualitative composition in both. However, i-RBC had higher ratios of saturated to unsaturated fatty acids and B. bovis cultures did not desaturate [14C] stearate. Cholesterol was the only sterol detected by GC-MS. Phospholipase A2 treatment of i-RBC and n-RBC revealed no enhanced hemolytic effects in i-RBC, suggesting that the erythrocyte membrane phospholipid composition is essentially unaltered by the parasite. Labeling of i-RBC or n-RBC with [125I] Bolton-Hunter resulted in an enhanced phosphatidylserine labeling in i-RBC. This study provides the first data on B. bovis lipid constitution and biosynthesis. They show that phosphatidylcholine formation is the main biosynthetic process in these cells. The striking differences in the contents of phosphatidylcholine between host erythrocytes and the parasite suggests that it may be a useful target for both chemotherapy and immunoprophylaxis against bovine babesiosis.
J Florin-Christensen; C E Suarez; M Florin-Christensen; S A Hines; T F McElwain; G H Palmer
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Molecular and biochemical parasitology     Volume:  106     ISSN:  0166-6851     ISO Abbreviation:  Mol. Biochem. Parasitol.     Publication Date:  2000 Feb 
Date Detail:
Created Date:  2000-05-10     Completed Date:  2000-05-10     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8006324     Medline TA:  Mol Biochem Parasitol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  147-56     Citation Subset:  IM    
Department of Veterinary Microbiology and Pathology, Washington State University (WSU), Pullman 99164-7040, USA.
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MeSH Terms
Babesia bovis / chemistry,  metabolism*
Carbon Radioisotopes
Cells, Cultured
Cholesterol Esters / biosynthesis
Chromatography, Thin Layer
Diglycerides / biosynthesis
Erythrocytes / drug effects,  metabolism,  parasitology*
Gas Chromatography-Mass Spectrometry
Iodine Radioisotopes
Lipid Metabolism*
Lipids / analysis,  biosynthesis
Phosphatidic Acids / biosynthesis
Phosphatidylcholines / analysis,  biosynthesis*
Phosphatidylinositols / biosynthesis
Phospholipases A / pharmacology
Phospholipases A2
Reg. No./Substance:
0/Carbon Radioisotopes; 0/Cholesterol Esters; 0/Diglycerides; 0/Iodine Radioisotopes; 0/Lipids; 0/Phosphatidic Acids; 0/Phosphatidylcholines; 0/Phosphatidylinositols; EC 3.1.1.-/Phospholipases A; EC A2

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