SMITH, A.M.*; STARTZ, T.; RAHME, D.; PIERCE, C.; Ithaca College, Ithaca, NY: Proteins characteristic of the adhesive mucus of molluscs and their potential role in determining gel function.

A variety of molluscs secrete adhesive forms of mucus that create powerful attachments. Research with limpets and periwinkle snails has demonstrated that the primary difference between these gels and typical, non-adhesive trail mucus is a substantial increase in specific proteins. We show that the same pattern occurs in two common terrestrial molluscs, the slug Arion subfuscus and the garden snail Helix aspersa. The adhesive mucus of the slugs contains significantly more protein than the trail mucus. This was due to a doubling of the concentration of two proteins with molecular weights of ~5 and 57 kD, with no increase in other proteins and carbohydrates. These two proteins account for roughly half of the organic material in the adhesive mucus. In the garden snail, the primary difference between the two forms of mucus is the presence of three proteins (87, 98 and 185 kD) that constitute more than half of the organic material in the adhesive mucus, but are absent from the trail mucus. In the slug and the garden snail, the differences in protein content were correlated with clear increases in the tenacity produced by the mucus. When used to glue test pieces together, the adhesive mucus of slugs created an average tenacity of 45 kPa, while the trail mucus at a similar concentration produced insignificant tenacity, often failing to hold the test pieces together. This is similar to results from limpets and periwinkles, which produce tenacities near 100 kPa when using adhesive mucus, and 2-6 kPa when using trail mucus. Because specific proteins are correlated with a large increase in tenacity in species from different environments, functional and biochemical comparison of these proteins should yield interesting insights.