The permeability of simian erythrocytes to choline was found to be considerably increased after infection by the malaria parasite, Plasmodium knowlesi. Choline entry occurs by a facilitated-diffusion system involving a carrier, which displays temperature-dependence, saturability with choline (Km = 8.5 +/- 0.
View Article and Find Full Text PDFThe asexual development of Plasmodium within the mature mammalian erythrocyte is associated with intense membrane biogenesis, notably to ensure the increase in the size of the parasite and of the parasitophorous vacuolar membranes PVM. A considerable increase in the content of most lipids except cholesterol [namely, phospholipids PL, neutral lipids, and fatty acids FA] occurs. The PL composition and the constitutive FAs of the parasite differ markedly from the original host cell membrane.
View Article and Find Full Text PDFThe biosynthesis of phospholipids is extensive in Plasmodium knowlesi-infected simian erythrocytes due to the synthesis of membranes by this single-cell eukaryote in a host erythrocyte devoid of any pathway for lipid biosynthesis. In the present paper, we show that the incorporation of [3H]glycerol, which reflects de novo biosynthesis, is better studied at 300 microM-1 mM than at the trace doses, since this non-physiological precursor does not modify the amount of phosphatidylcholine biosynthesis from [3H]choline. Time-course incorporation of radioactive glycerol, oleate, lysophosphatidylcholine, choline, and inositol in RPMI 1640 medium containing nutrients for lipid synthesis showed that the optimum incubation time for phospholipid studies is 60-90 min, after which radioactive incorporation slows considerably.
View Article and Find Full Text PDFThe effect of the antimalarial drug chloroquine (CQ) on the phospholipid metabolism in Plasmodium knowlesi-infected simian erythrocytes has been studied by incubating cells with different labeled precursors and various concentrations of CQ. The drug induced considerable modifications of this metabolism but at the same time decreased nucleic acid and protein synthesis as well as the output of 14CO2 from radioactive glucose. Phosphatidylcholine biosynthesis was severely reduced.
View Article and Find Full Text PDFCDPcholine: 1,2-diacylglycerol cholinephosphotransferase (EC 2.7.8.
View Article and Find Full Text PDFA number of choline and ethanolamine analogs were evaluated as inhibitors of P. falciparum growth in vitro. 1-Aziridineethanol, DL-2-amino-1,3-propranediol and D- or L-2-amino-1-butanol were the most efficient inhibitors of parasite multiplication, with an IC50 of 50-80 microM, whereas numerous other analogs were less active.
View Article and Find Full Text PDFMetabolic pathways leading to phospholipid biosynthesis in Plasmodium-infected simian erythrocytes were tested and quantified by incubating leucocyte-free erythrocytes in the presence of labelled precursors. Plasma fatty acids and lysophospholipids both served as sources of the fatty acids required for cellular phospholipid biosynthesis. However, the entry of free fatty acids and lysophospholipids appeared to be controlled by a competitive mechanism.
View Article and Find Full Text PDFThe metabolism of phospholipids in synchronous Plasmodium falciparum-infected erythrocytes was studied over one cycle of 48 h by the incorporation of labeled palmitate, serine, choline, and myo-inositol into cellular lipids. The rates of incorporation of palmitate and serine into total phospholipids and of choline into phosphatidylcholine (PC) were linear with the maturation of the parasite, increasing by a factor of 2-5.6 according to the precursors.
View Article and Find Full Text PDFMol Biochem Parasitol
March 1982
D vitamins are effective inhibitors of the in vitro intraerythrocytic growth of Plasmodium falciparum. Disappearance of the parasitemia was observed after 48 h contact between infected cells and 5 x 10(-6) M 1 alpha-hydroxycholecalciferol, 5 x 10(-5) M 25-hydroxycholecalciferol (25-OH-D-3), 1 alpha, 25-dihydroxycholecalciferol or 2.5 x 10(-4) vitamin D-2 and D-3.
View Article and Find Full Text PDFC R Acad Hebd Seances Acad Sci D
April 1977
The (Na+-K+)-dependant ATPase prepared from human erythrocyte ghosts has been purified with sodium deoxycholate in a high ionic medium. After the purification, 60% of the native activity bound to the membranes was recovered.
View Article and Find Full Text PDFComp Biochem Physiol B
January 1972
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