An autoradiographic and biochemical analysis of palmitate incorporation into fat body lipid

Abstract

Short-term in vitro experiments demonstrated that 14C-palmitate is rapidly esterified by fat body from several developmental stages of Hyalophora cecropia. Triglyceride is the major product when larval or adult fat body is utilized while diglyceride accumulates during the 3 hr incubation period with fat body from pharate pupae, diapausing pupae, and chilled pupae. Similar results were obtained with pupae of Philosamia cynthia, Antheraea polyphemus, and Hyalophora gloveri. The pattern of incorporation with Leucophaea maderae fat body is essentially the same as that found in H. cecropia larval fat body. The synthesis of glycerides can be followed with light microscope autoradiography and the data suggest that 3H-palmitate is esterified in the endoplasmic reticulum and then transported to the lipid globules which are the depository for glyceride storage. Electron microscope autoradiographic studies support this supposition.