ARACHIDONIC-ACID AND PROSTAGLANDIN E(2) IN MALPIGHIAN TUBULES OF FEMALE YELLOW-FEVER MOSQUITOS

The fatty acid compositions of Malpighian tubules from adult females o f the mosquito Aedes aegypti were determined for total lipids, phospho lipids, triacylglycerols and three phospholipid fractions, namely phos phatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylin ositol/phosphatidylserine (PI/PS). The prostaglandin precursor arachid onic acid (20:4n-6) occurred in total lipids and phospholipids, but no t triacylglycerols. Within phospholipids, nearly all of the 20:4n-6 wa s detected in PC, with only traces in PE, and none was detected in PI/ PS. Isolated Malpighian tubules incorporated exogenous radioactive 20: 4n-6 into tissue phospholipids and diacylglycerols, with most of the r adioactivity recovered in diacylglycerol. These data indicate selectiv e incorporation of 20:4n-6 into tissue lipids. PGE2 Was detected in Ma lpighian tubule whole mounts by immunohistochemical staining. These fi ndings support the idea that prostaglandins are physiologically active in mosquito Malpighian tubules.