DEFENSE-MECHANISMS IN INSECTS - CERTAIN INTEGUMENTAL PROTEINS AND TYROSINASE ARE RESPONSIBLE FOR NONSELF-RECOGNITION AND IMMOBILIZATION OF ESCHERICHIA-COLI IN THE CUTICLE OF DEVELOPING CERATITIS-CAPITATA

A defense mechanism in the cuticle of developing C. capitata was demon strated using an in vitro system consisting of isolated cuticular tyro sinase from C. capitata, cuticular tyrosinase-free proteins, tyrosine, and E. coli. The simultaneous presence of the above components result ed in the formation of large immobilized E. coli aggregates. By contra st, omission of any of the above components failed to produce such agg regates. In other words, E. coli retained their mobility and viability . The results indicate that certain cuticular proteins are responsible for the nonself-recognition, since they are able to bind to the E. co li surface in vitro, and a reactive tyrosine derivative is generated b y the action of cuticular tyrosinase for the immobilization and probab ly killing of E. coli. Based on these studies the most likely explanat ion for the nonself-recognition and immobilization and/or killing of b acteria is the production of E. coli-protein complexes and their cross linking through quinone intermediate. (C) 1993 Wiley-Liss, Inc.