VARIATIONS IN THE DENSITY OF LIPOPHORINS DURING LATE LARVAL AND EARLYPUPAL DEVELOPMENT OF MANDUCA-SEXTA

The density of lipophorin was determined in individual Manduca sexta d uring development from the second day of the fifth larval instar to th e second day of the pupal stage. Lipophorin formed defined bands when subjected to density gradient ultracentrifugation. All lipophorin obse rved was high density lipophorin; however, the densities varied from 1 .100 to 1.184 g/ml, and 40% of the animals had more than one density f orm of lipophorin. The lipophorins were divided into five density clas ses: class 1 from 1.100 to 1.113 g/ml, class 2 from 1.114 to 1.132 g/m l, class 3 from 1.133 to 1.145 g/ml, class 4 from 1.146 to 1.162 g/ml, and class 5 from 1.163 to 1.184 g/ml. In feeding larvae, classes 2 an d 3 were the most abundant. Larvae of the first day of wandering had e ither lipophorin in class 2 or in classes 2 and 5. Later during wander ing the variation increased, but on the third day most of the lipophor in was in class 2. In first day pupae, only lipophorins of classes 4 a nd 5 were detected, while on the second day of the pupal stage, classe s 2 and 3 were predominant. Class 1 lipophorin was abundant in larvae injected with Manduca adipokinetic hormone (M-AKH), and rare in young feeding larvae. In no other stage was class 1 lipophorin observed. Our results show that the density of lipophorin is much more variable tha n previously reported which makes it difficult to ascribe any lipophor in density to a developmental stage. These results also show that adip okinetic hormone decreases the density of lipophorin in larvae. (C) 19 96 Wiley-Liss, Inc.