De novo Synthesis and Levels of Cytochrome c and a Biliprotein during Pupal-Adult Development of a Butterfly, Pieris brassicae
Abstract Using a sensitive pH-difference spectroscopic method in combination with a three-column procedure of ion-exchange chromatography (overall yield 94%) the levels of cytochrome c in the large white butterfly, Pieris brassicae, were determined from the last larval instar to the adult insect. In the larva cytochrome concentration reached a maximum at mid instar and subsequently decreased to very low values in the pupa. During adult development the level of cytochrome c increased 50-fold in males and 43-fold in females; this sexual difference was expressed only after adult emergence. Biliverdin IXγ which occurs as a specific biliprotein complex was accumulated during the last larval instar and also in young butterflies. De novo synthesis of heme c, biliverdin IXγ and the corresponding apoproteins was demonstrated in newly emerged butterflies by injections of radiolabeled 5-aminolevulinate, lysine, leucine, and succinate, respectively. Cycloheximide inhibited labeling of both apoproteins and of heme c to 90% but that of the bilin to only 25%. This suggests that in cytochrome c but not in the biliprotein formation of the holoprotein depended on a coordinated synthesis of both constituents. Incorporation of 5-aminolevulinate into the biliprotein exceeded that into cytochrome c sevenfold indicating that biliverdin IXγ is the major product of the heme pathway in P. brassicae. The results are discussed in relation to the formation of mitochondria and flight muscles during postembryonic development of insects.