After determining the optimal conditions under which to manufacture radioactively labeled arylphorin at a high specific activity (using larvae fifth instar fat body), the arylphorin was injected into pharate adults (in pupa)--some at middle stage development (days 6 to 12 of pharate adult development) and some at late stage development (days 12 to 17 in pharate adult development). Radiolabeled phenylalanine (one of the amino acids that composes arylphorin) was also injected into insects in the same life cycle periods, middle and late stage pharate adults, though not the same insects--different M.sexta were injected with labeled arylphorin than were injected with labeled phenylalanine.
The "behaviors" of the two labeled molecule were traced and compared for both development stages. Of specific concern was CO2 produced and presence/concentration of the label in tissues, and the period in the life cycle during which these events occured. The purpose of the comparison results was to reveal the function of arylphorin--a storage protein to be degraded into the free amino acid pool, or a molecule used directly in the construction of tissues, specifically the cuticle.