The roles of Sarcophaga defense molecules in immunity and metamorphosis

This article summarizes recent progress (1996 1998) in our studies on self-defense molecules in Sarcophaga peregrina. A new antibacterial substance was purified and its unique structure and function revealed a novel aspect of the Sarcophaga defense system. We found a novel lectin and cysteine protease in hemocytes which will assist in the understanding of immune response of hemocytes. There have been two major advances in research on the regulation of defense gene induction: (i) cDNA cloning of a new transcriptional factor binding to the kappaB-like promoter sequence of the Sarcophaga lectin gene, (ii) methylation of cytosolic factors essential for induction of immune genes in the fatbody. Metamorphosis is an interesting event from an immunological point of view: (i) a novel protease with antibacterial activity was discovered from metamorphosing gut, and (ii) a pupal hemocyte-specific surface antigen was purified and characterized in terms of its structure and possible function for larval tissue recognition and elimination.