Lipid biology of Cryptosporidium parvum and Eimeria nieschulzi (Apicomplexa).

摘要

Lipid membrane biology of members of the phylum Apicomplexa is largely unexplored. Lipid pathways represent potential targets for chemotherapy, especially if there are parasite-specific element in lipid synthesis. In order for these targets to be discovered, the basic lipid biology of apicomplexans needs to be examined. Therefore, two mammalian coccidia, Cryptosporidium parvum and Eimeria nieschulzi, were chosen as models to elucidate lipid composition.; Membrane lipids of C. parvum and Madin-Darby bovine kidney (MDBK) cells, an epithelial-like cell line commonly used to study coccidia in vitro, were analyzed using both thin-layer and gas-liquid chromatography. Phosphatidylcholine was the predominant lipid in each, comprising 65% and 41% of the total phospholipids, respectively. Phospholipids of C. parvum contained twice the level of 16:0 and twenty-fold more 18:2 than MDBK cells. The parasite may sequester specific complex membrane lipids at concentrations greater than those in the host cells. This study constitutes the first report of the lipid composition of C. parvum.; Membrane lipid compositions of both sporulated and unsporulated oocysts of the rat coccidian, Eiemria nieschulzi, were also similarly analyzed. The predominant lipid in both sporulated and unsporulated oocysts was phosphatidylcholine, comprising 75% and 85% of total phospholipids, respectively. The predominant fatty acid was oleic acid (18:1). Numerous primary alcohols, including C20, C22, C24, and C26, were detected in the neutral lipid fraction of both sporulated and unsporulated oocysts, in addition to cholesterol. Although changes occurred in lipid composition during sporulation, differences appeared minor. This study constitutes the first report of the lipid composition of E. nieschulzi.; Two lipid supplements conjugated to bovine serum albumin were tested for their effects on early phase growth of E. nieschulzi in vitro. The fatty acids 14:0 and 18:2 were selected because they were present at higher levels in the parasite than in MDBK cells. Neither fatty acid improved parasite growth and development over that achieved with 10% fetal bovine serum alone.