ALLATOSTATIN IN HEMOCYTES OF THE COCKROACH DIPLOPTERA-PUNCTATA

Allatostatins are neuropeptides that inhibit the production, by the co rpora allata, of a major insect hormone, juvenile hormone. These pepti des are produced by cells of the brain and ganglia as well as by mid,o ut endocrine cells. Transport from these sites may contribute to the a llatostatin content in the hemolymph (insect blood). Using a monoclona l antibody against Diploptera punctata allatostatin I (A-P-S-G-A-Q-R-L -Y-G-F-G-L-NH2) and in situ hybridization with a digoxigenin-labeled c RNA probe generated from a portion of the allatostatin gene, it is dem onstrated that allatostatin is present in and synthesized by granular hemocytes of D. punctata. About 5% of the hemocytes react with anti-al latostatin antibody and a similar number hybridize with a cRNA probe t hat detects allatostatin-specific mRNA. Electron micrographs showed th at allatostatin-immunoreactive material occurs in membrane-bound, unif ormly dense granules that frequently fill fusiform-shaped cells. Allat ostatin in cell and plasma fractions of hemolymph quantified by enzyme -linked immunosorbent assay and by bioassay for inhibition of juvenile hormone synthesis in vitro indicated that about equal quantities (0.1 -0.2 fmol/mu l) are present in cell and plasma fractions. The producti on of allatostatin by hemocytes suggests that allatostatins may functi on as regulatory peptides in hemolymph activities in addition to their other known functions.