Classes of integument peptides

Abstract

Flurography of the products released from isolated integument of Calpodes ethlius (Lepidoptera: Hesperiidae) has shown that the epidermis synthesizes and secretes peptides into both the cuticle and hemolymph. The most abundant of these peptides have now been isolated and purified by preparative gel electrophoresis. Polyclonal antibodies have been developed against them and their activity and specificity determined by Western blot analysis. The antibodies have been used to confirm the location of the peptides. Immunoblots of the in vitro translation products of total epidermal mRNA confirm the epidermis' ability to synthesize these peptides. Immunogold labeling of sections for electron microscopy confirm the destination of the epidermal secretions in cuticle, in hemolymph, or in both locations. They include 180, 55, 43, 36, 30, 17 and 11 kDa peptides in the cuticle, 235, 45, 23 and 14 kDa peptides in the hemolymph and 89, 92, 71, 53 and 19 kDa peptides in both cuticle and hemolymph. Although these hemolymph peptides may be absent or rare in surface cuticle, some of them occur in the cuticle of tracheae. In addition to the three classes of epidermally synthesized peptides, a fourth class not synthesized by the epidermis at the time of deposition (66 and 48 kDa) are present in both cuticle and hemolymph. We conclude that Calpodes epidermis is involved with four classes of protein routing. The epidermis synthesizes and secretes peptides basally, apically and in both directions, and it probably transports proteins to the cuticle from the hemolymph.