Chu F E, Soudant P, Volety A K, Huang Y
Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA.
Exp Parasitol. 2000 Aug;95(4):240-51. doi: 10.1006/expr.2000.4533.
Uptake, distribution, and interconversion of fluorescent lipid analogs (phosphatidylcholine, PC; cholesteryl ester, CHE; phosphatidylethanolamine, PE; palmitic acid, C16; sphingomyelin, SM) by the two life stages, meront and prezoosporangium, of the oyster protozoan parasite, Perkinsus marinus, were investigated. Class composition of these two life stages and lipid contents in meront cells were also examined. Both meronts and prezoosporangia incorporated and modified fluorescent lipids from the medium, but their metabolic modes differ to some extent. Results revealed that among the tested analogs, neutral lipid components (CHE and C16) were incorporated to a greater degree than the phospholipids (PC, PE, and SM). HPLC analysis of meront lipids showed that while the majority of the incorporated PC, CHE, and PE remained as parent compounds, most of the incorporated C16 was in triacylglycerol (TAG) and SM was in ceramide and free fatty acids. The cellular distribution of fluorescent labels varied with lipid analogs and the extent of their metabolism by the parasite. Fluorescence distribution was primarily in cytoplasmic lipid droplets of both life stages after 24 h incubation with PC. After 24 h incubation with SM, fluorescence appeared in the membrane and cytosol. Total lipid contents in meront cultures increased during proliferation and TAG accounted for most of the increased total lipids. Since total lipid content per meront cell did not increase until the day of culture termination, the lipid increase in the meront culture was mainly a result of increased cell numbers. Both life stages contain relatively high levels of phospholipids, 53.8% in 8-day-old meronts and 39.4% in prezoosporangia. PC was the predominant phospholipid.
研究了牡蛎原生动物寄生虫——马氏帕金虫（Perkinsus marinus）的两个生命阶段（裂殖体和前游动孢子囊）对荧光脂质类似物（磷脂酰胆碱，PC；胆固醇酯，CHE；磷脂酰乙醇胺，PE；棕榈酸，C16；鞘磷脂，SM）的摄取、分布和相互转化。还检测了这两个生命阶段的类别组成以及裂殖体细胞中的脂质含量。裂殖体和前游动孢子囊都从培养基中摄取并修饰荧光脂质，但其代谢模式在一定程度上有所不同。结果表明，在测试的类似物中，中性脂质成分（CHE和C16）的摄取程度高于磷脂（PC、PE和SM）。对裂殖体脂质的HPLC分析表明，虽然大部分摄取的PC、CHE和PE仍为母体化合物，但大部分摄取的C16存在于三酰甘油（TAG）中，而SM存在于神经酰胺和游离脂肪酸中。荧光标记的细胞分布因脂质类似物及其被寄生虫代谢的程度而异。与PC孵育24小时后，荧光分布主要在两个生命阶段的细胞质脂质滴中。与SM孵育24小时后，荧光出现在膜和细胞质中。裂殖体培养物中的总脂质含量在增殖过程中增加，TAG占总脂质增加量的大部分。由于每个裂殖体细胞的总脂质含量直到培养终止日才增加，裂殖体培养物中的脂质增加主要是细胞数量增加的结果。两个生命阶段都含有相对较高水平的磷脂，8日龄裂殖体中为53.8%，前游动孢子囊中为39.4%。PC是主要的磷脂。
