Structural and biochemical analysis of the parasite Gordius villoti (Nematomorpha, Gordiacea) cuticle

The cuticle of the nematomorpha Gordius villoti is a proteinaceous extracellular structure that covers the body during the endoparasitic life in the hemocoelic cavity of insect hosts, and of the free-living adult animals. The ultrastructure of the cuticle has a complex spatial organization with several parallel layers of large diameter fibres, interposed thinner fibrous elements and honeycomb-shaped matrix surrounding the fibers. When adult isolated cuticles were partially solubilized by several compounds, the structure revealed a strong insolubility and the main fibers were always observable. HPLC and spectrophotometric assays carried out to investigate the presence of tyrosine cross-linking, indicated such a mechanism as a key-element in the hardening process of the cuticle. Such data strongly suggest that the Gordius cuticle contains dityrosine compounds, whose formation is probably mediated by endogenous peroxidase activity. (C) 2000 Harcourt Publishers Ltd.