STRUCTURAL FORMS AND POSSIBLE ROLES OF ALIGNED CYTOSKELETAL BIOPOLYMERS IN HAGFISH (SLIME EEL) MUCUS

The hagfish, marine benthic dwellers, are primitive vertebrates which, upon stress, secrete massive quantities of mucus from slime glands of the integument by the holocrine mode. Lysis of each gland thread cell releases a single, intermediate filament-rich thread (∼ 60 cm × 1.5 μm), which collectively modulates the hydration and cohesiveness of mucus. In this report, with the Pacific hagfish (Eptatretus stouti), we showed that the threads exhibit a tendency for self-assembly into novel, aligned and intertwined cytoskeletal aggregates ("cables"). Large cables (15-40 cm in length, 50-800 μm in width) can be physically prepared from the whole mucous exudate, but similar smaller cables (0.1-10 cm in length, 50-200 μm in width) were found occurring naturally, particularly at the ends of laid eggs. Threads and cables may facilitate adhesion of mucus to the integument of the fish, restrict eggs to an optimum spawning site, and abet defense against invasive organisms. © 1991.