P. Soudant et al., Lipid class composition of the protozoan Perkinsus marinus, an oyster parasite, and its metabolism of a fluorescent phosphatidylcholine analog, LIPIDS, 35(12), 2000, pp. 1387-1395
Perkinsus marinus is one of two important protozoan parasites of the easter
n oyster, Crassostrea virginica. The other is Haplosporidium nelsoni. Lipid
s extracted from 7-d-old in vitro cultured P. marinus meronts, incubated wi
th fluorescent-labeled phosphatidylcholine (FL PC) and nonincubated P. mari
nus meronts, were analyzed by a high-performance liquid chromatography (HPL
C) system equipped with a diol phase column, in combination with thin-layer
chromatography coupled with a flame-ionization detector (TLC/FID), and hig
h-performance thin-layer chromatography (HPTLC). Various polar and neutral
lipid classes were separated by HPLC using a two-gradient solvent system. F
ive polar lipid classes-phosphatidylcholine (PC), phosphatidylethanolamine
(PE), cardiolipin (CL), sphingomyelin (SM), and phosphatidylserine (PS)-wer
e identified from P. marinus extracts. Four neutral lipid classes-triacylgl
ycerol (TAG), steryl ester (SE), cholesterol (CHO), and fatty alcohol-were
distinguished. TLC/FID analysis of meront lipids showed that the weight per
centages of PC, PE, CL, SM, PS/PI, TAG, SE, and CHO were 21, 10.7, 4, 2.3,
4.3, 48.7, 7.8, and 1.2%, respectively. HPLC and HPTLC analyses revealed th
e presence of two SM and PS isomers in P. marinus extracts. Perkinsus marin
us effectively incorporated FL PC acquired from the medium and metabolized
it to various components (i.e., free fatty acid, monoacylglycerol, diacylgl
ycerol, TAG, PE, and CL). Uptake and interconversion of FL PC in P. marinus
meronts increased with time. After 48 h the total uptake of fluorescence (
FL) was 28.9% of the FL PC added to the medium, and 43% of the incorporated
FL resided in TAG.