Published online by Cambridge University Press: 01 June 2008
The transformation from larval caterpillar to non-feeding pupa and adult moth involves a complete remodelling and restructuring of an insect and its organs. In the groundnut pest Amsacta albistriga Walker, the female sex-specific storage protein 1 (SP1) was monitored from last larval instars, during pupal development to the adult stage. Staining intensity of SP1 (which resolved at 82 kDa) in the peripheral fat body (PF) tissues subjected to 10% SDS-PAGE was maximum at mid-stage last larval instars and declined subsequently. However, in perivisceral fat body (PVF) tissues, the staining intensity of SP1 increased significantly from mid-stage final instar. The presence of SP1 during pupal ovary and adult ovariole development and its availability during egg development was confirmed by immunoblot analysis. Electron microscopy data revealed that the decline of biosynthesis of SP1 in PF tissues and its disintegration were associated with the appearance of irregular nucleus and autophagic vacuoles during transformation of larva to pupa. In vitro and in vivo studies using [35S]-methionine-labelled storage proteins showed that, unlike PF tissues, PVF tissue sequestered a significant amount of labelled SP1. During this transformation, SP1 was mainly sequestered as storage protein granules until they served as sources of amino acids for the production of egg yolk proteins. Localization of clathrin-coated pits and crystalline storage proteins was confirmed by immunogold tracer techniques.