Distribution of arachidonic acid among phospholipid subclasses of lone star tick salivary glands.
The subclass composition of choline- and ethanolamine-containing phospholipids was determined by analysis of acyl-linked fatty acids released by base hydrolysis of diradylglycerobenzoates formed from lone star tick salivary gland diacyl, alkylacyl and alkenylacyl phospholipids. The diacyl subclass comprises 87% of all choline-containing phospholipids, while th alkylacyl subclass comprises c. 9% and the alkenylacyl subclass c. 4%. The diacyl subclass comprises 72-77% of ethanolamine-containing phospholipids and about 14 and 13% of this subclass of phospholipid are alkylacyl and alkenylacyl lipids, respectively. Arachidonic acid (20:4) is the most abundant fatty acid (28% of all fatty acids) esterified in the alkylacyl form of phosphatidylcholine (PC) and it comprises 17% of the fatty acids in alkenylacyl-PC. The alkylacyl form of phosphatidylethanolamine (PE) is also rich in 20:4 (24%) while the alkenylacyl-PE subclass contains only 9% 20:4. Despite the relatively high amounts of 20:4 within the ether-linked phospholipids, the majority of the salivary gland 20:4 (> 83%) is found in the diacyl phospholipid subclass because of the preponderence of this subclass in tick salivary glands. Isolated salivary glands incorporated [3H]-20:4 primarily (> 98%) into the sn-2 position of diacyl PC > PE, with some incorporation into triglycerides. Continued incubation in the absence of labeled 20:4 demonstrated remodeling of [3H]-20:4 from PC into PE, and from the diacyl subclass to the alkylacyl subclass in the choline containing phospholipids.
Shipley
M M
MM
Department of Entomology, Oklahoma State University, Stillwater 74078.
Dillwith
J W
JW
Bowman
A S
AS
Essenberg
R C
RC
Sauer
J R
JR
D000818:Animals; D016718:Arachidonic Acid / Q000032:analysis* / Q000378:metabolism; D002855:Chromatography, Thin Layer; D007700:Kinetics; D010743:Phospholipids / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011865:Radioisotope Dilution Technique; D012469:Salivary Glands / Q000737:chemistry* / Q000378:metabolism; D013987:Ticks; D014316:Tritium
D010743:Phospholipids; D014316:Tritium; D016718:Arachidonic Acid