For vertebrate animals living in as aqueous environment mucus plays an important role in their survival. Studies with the hagfish (eptatretus stoutii), a primitive vertebrate and a copious secretor of mucus, suggest an intermingling of mucins synthesized by one cell-type (mucous cells) with aggregates of unusual keratin-like intermediate filaments (IFs) from another cell-type (thread cells). Interaction of these components results in a change in rheological properties and a cohesiveness which we hypothesize serves to facilitate the multifaceted functions of mucus, including its biological activity. The overall aim of the proposal is to expand these observations in selected teleost species (e.g. intertidal fish, parrotfish) in which mucus exerts notable protective roles. Major objectives to be achieved by immunological and biochemical procedures are (1) identify and characterize cytoskeletal components, particularly IF aggregates,released from specific epidermal cell types: (2) determine if these aggregates can modulate the rheological properties of mucus or provide binding sites for secretable biologically active substances such as the hemagglutinins/lectins; (3) determine the cellular origin of thel atter compounds and their specificity for some microorganisms; (4) determine the sequence (cDNA methodology) of the a,B and y polypeptides from hagfish thread cells as a means to understand thread assembly in which IFs attain parallel alignment and a change in polypeptide composition occurs during differentiation and terminal maturation; (5) establish whether the hagfish IFs possess unique keratin like sequences or if they represent a prototype for filamentous aggregates synthesized and released by specific epidermal cells of teleosts. These studies have great significance with respect to the biochemistry and structural features of intermediate filaments, as well as the biochemical evolution of intermediate filaments. The studies also have major significance with respect to material defense mechanisms of teleost fish. Finally, these studies may lead to practical applications, such as the development of novel biomaterials for lubrication or extiles.
