Advisor: Gerhard Steiner

PhD Defensio - Friday, September 11th 2026, 11:00
SR 4.1, UBB, Djerassiplatz 1, 1030 Vienna 

Abstract  

The New Zealand endemic freshwater gastropod, Latia neritoides, is known as the only freshwater snail using bioluminescence as a unique, active defence mechanism. When stressed, L. neritoides releases a luminescent, sticky, greenish mucus, which serves to obscure vision of the attacker and adhere to it. Although the four key components of the Latia bioluminescence system are described, the morphological origin, composition and the interaction between the different components remains unsolved. This study indicates that the defensive secretion is a specialized, two-component system derived from different glands. Morphological and histochemical results suggest that two prominent subepithelial gland types, L1l and L2l, which are present in the lateral foot area of L. neritoides, are plausible candidates for the production of the adhesive component. The bioluminescent components are likely to originate from two common gland types (Lmcg1 and Lmcg2) located in the roof of the mantle cavity, which show a high protein synthesis activity.

Protein analysis showed that the defence mucus of Latia neritoides contains highly abundant proteins like hemocyanin and a unique physalysin-like protein. The transcript sequence of this adhesion-related protein is rich in cysteine residues, suggesting potential disulfide cross-linking important for adhesive strength.

Overall, the results provide strong support for the hypothesis that the defence mechanism of L. neritoides relies on a specialized two-part secretion, where the adhesive part and the bioluminescent compound mix upon release, utilizing the pneumostome area.