REGULATION OF SERPIN GENE-1 IN MANDUCA-SEXTA

Hemolymph of Manduca sexta contains proteins from the serpin superfami ly, which are inhibitors of serine proteinases. We have used probes sp ecific for M. sexta serpin gene-1 mRNA and protein to study the expres sion and hormonal regulation of this gene. Serpin gene-1 is expressed at a high level in larval fat body and at a lower abundance in hemocyt es, where serpin protein is localized in the granules of granular cell s. Serpin gene-1 mRNA is abundant in the fat body of feeding fourth an d fifth instar larvae, but disappears abruptly at molts and at the wan dering stage. The concentration of serpin proteins in hemolymph during development is correlated with the abundance of serpin mRNA in fat bo dy. Results of in vivo and in vitro experiments indicate that 20-hydro xyecdysone has a role in negative regulation of serpin gene-1.