The expression and sequestering of methionine-rich storage hexamerins in A. polyphemus during second pupal development

A set of gene expression markers which occurs during larval to pupal metamorphosis in the saturniid moths is the synthesis of a pair of hemolymph methionine-rich hexamerins (M-MtH and V-MtH) and their uptake into the fatbody. These hexamerins were studied in the juvenile hormone induced second pupae using the moth Antheraea polyphemus. Relative concentrations of M-MtH and V-MtH in the hemolymph and soluble fatbody extract were measured with the 5th instar larvae, pharate adults, and second pupae. The ontogeny of the M-MtH and V-MtH in the hemolymph of the second pupae when compared to the normal larvae and normal pharate adults, follows the pattern of the pharate adult. The ontogeny of the M-MtH and V-MtH in the fatbody of the second pupae when compared to the normal larvae and normal pharate adults, follows the pattern which is not like that of the developing 5th instar larvae or the pharate adult.

When Hyalophora cecropia hemolymph was injected into wandering larvae, diapausing pupae, day-5 pharate adults, and day-5 second pupae of Antheraea polyphemus, the H. cecropia's M-MtH and V-MtH were taken into the larval and second pupal fatbody but not to the normal pharate adult fatbody. Thus, the results show a positive evidence that JH causes the reexpression of pupal genes in the fatbody of the second pupae. Furthermore, the injected ³H-leucine was found to be incorporated into M-MtH in second pupae, but not in the normal pharate adults.

These results support the theory that the action of JH in the second pupae is to reexpress the genes which are expressed during the larval to pupal transformation.