In the study, a research team led by Georgia State University biologist Charles Derby, PhD, examined the ink and opaline glands of Aplysia sea slugs for the chemicals L-lysine, L-arginine and an enzyme protein called escapin. In previous research, Derby's team determined that escapin mediates the chemical reaction with L-lysine and L-arginine that results in the defensive secretion. Using a variety of chemical and molecular techniques, the scientists identified L-lysine and L-arginine in the opaline gland, which produces the sticky white component of the secretion, and escapin in the ink gland, which produces the purple dye in the secretion.
"Aplysia packages these innocuous precursors separately and then releases them simultaneously into its mantle cavity at the precise time when they are needed," explained Derby. "This mechanism insures the secretion's potency against attacking predators to enable sea slugs to escape."
Aplysia employs a variety of mechanisms to defend against predators. Its secretion stimulates feeding behaviors in spiny lobsters, but deters these behaviors in other animals. In previous studies, Derby and his team also identified an antimicrobial property in the secretion resulting from the chemical reaction between escapin and L-lysine. The scientists are currently examining the chemical process that results in the antimicrobial component and also are attempting to identify Aplysia predators
Contact: Ann Claycombe
Georgia State University