Protein composition of the threat induced epidermal secretion from the Arabian Gulf catfish, Arius Thalassinus (Ruppell)

1. 1. When threatened or injured, the Arabian Gulf catfish (Arius thalassinus, Ruppell) secretes a thick gel-like layer of proteinaceous material to its skin surface mainly from unicellular glands of the epidermis termed club cells. 2. 2. Since a preparation from this secretion has been implicated in stimulation of the rate of wound healing in man and other test animals, the total gel protein composition was analysed by chemical, chromatographic and electrophoretic techniques. 3. 3. Gel proteins were separated into soluble and insoluble fractions by extraction with increasingly strong solubilizing agents and the most insoluble components were solubilized only upon treatment with 10% SDS or concentrated organic acids. 4. 4. Some of the soluble proteins from the secretion are also present in the insoluble protein fractions, indicating that the insoluble material is formed in part by aggregation of the soluble proteins. 5. 5. The secretion was shown to be distinct from the catfish venom and differed greatly from typical fish mucus secretion in its composition and distribution of protein components.