INDUCTION OF NOVEL PROTEINS IN MANDUCA-SEXTA AND BLABERUS-GIGANTEUS AS A RESPONSE TO FUNGAL CHALLENGE

The induction of proteins in the tobacco hornworm larvae, Manduca sext a, and the adult tropical cockroach, Blaberus giganteus, was examined after challenge with cell walls of the entomopathogenic fungus Metarhi zium anisopliae or the yeast, Saccharomyces cerevisiae. This was compa red to induction of proteins after challenge with beta-1,3-glucan or c ell malls from the bacterium Micrococcus lysodeikticus. induction of p roteins was examined in live insects, in vitro cultures of fat bodies excised from insects, or an embryonic cell line from Mi. sexta, MRRL-C H-1. Challenge of fifth instar larvae by injection with S. cerevisiae resulted in the induction of 14- and 33-kDa proteins after 24 hr, Chal lenge of fat bodies with M. anisopliae cell wails resulted in the indu ction of several proteins which were not induced after challenge with beta-1,3-glucan or M. lysodeikticus. These inducible proteins did not immunoreact with M. sexta alaserpin or M13 (hemolin) antibodies, Howev er, one of the proteins ica. 33 kDa) induced in M. sexta by S. cerevis iae, beta-1,3-glucan, M. anisopliae cell walls, or cell malls of M. ly sodeikticus immunoreacted with antibodies for scolexin. Over 300 prote in species were synthesized by B. giganteus fat bodies after a 6-hr in cubation and approximately 10 novel proteins were observed after chall enge with fungal cell walls. M. sexta cell cultures also responded to challenge with fungal cell walls by synthesizing several novel protein s, The results suggest that holometabolous and hemimetabolous insects synthesize novel proteins in response to fungal challenge and that sit es of synthesis may be in different cell types (fat bodies or epiderma l cells).