Meeting Abstract
Hagfishes defend themselves from fish predators by producing defensive slime consisting of mucous and thread components that interact synergistically with seawater to pose a suffocation risk to their attackers. Deployment of the slime occurs in a fraction of a second and involves hydration of mucous vesicles as well as unraveling of the threads from their elaborately coiled state to their full length of approximately 150 mm. Previous work has shown that unraveling of coiled threads (or “skeins”) in Atlantic hagfish requires vigorous mixing with seawater as well as the presence of mucus, whereas skeins from Pacific hagfish tend to unravel spontaneously in seawater. Here we explored the mechanisms that underlie these different unraveling modes, and focused on the molecules that make up the skein glue, a material that must be disrupted for unraveling to proceed. We found evidence that M. glutinosa possesses skein glue, and that it is less soluble in seawater than E. stoutii glue. Using SDS-PAGE, mass spectrometry, and transcriptomics, we identified several putative skein glue proteins that are expressed in the slime glands of both species. We identified 14 protein sequences that are likely glue components, with three of them being highly charged acidic proteins that lack homology with any other proteins. Although the ecological significance of the two modes of skein unraveling described here are unknown, they may reflect differences in predation pressures, with selection for faster skein unraveling in the Eptatretus lineage leading to more soluble glue.
