In vitro studies on the release and transport of phospholipids.

Abstract

When incubated in vitro, fat body from several developmental stages of the silkmoth, Hyalophora cecropia, and from the cockroaches, Leucophaea maderae and Periplaneta americana, has the ability to incorporate labelled precursors into phospholipid. When this ‘prelabelled fat body’ is reincubated in unlabelled medium containing haemolymph, radioactive phospholipids are released into the incubation medium. Flight muscle placed into an incubation medium containing radioactive phospholipids is capable of incorporating some of this phospholipid into flight muscle phospholipid. The majority of the labelled phospholipid released from the prelabelled fat body consists of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Electrophoretic analysis of the haemolymph containing incubation medium revealed that phospholipids released from the fat body were conjugated to specific haemolymph proteins. One of these lipoproteins is thought to be analogous to the high-density lipoproteins of mammalian blood. The study suggests that insect fat body has the capacity to synthesize phospholipids from simple precursors and release this phospholipid into the haemolymph from where it is transported in the form of lipoprotein.