Phytochelatins are metal-binding metabolites found in almost
all plant species and some animal groups, including nematodes and
annelids, where they can play an important role in detoxifying metals
such as cadmium. Species from several other taxa contain a phytochelatin
synthase (PCS) gene orthologue, including molluscs, indicating they may
have the potential to synthesize phytochelatins. However, the presence of
a gene alone does not demonstrate that it plays a functional role in
metal detoxification. In the present study, we show that the aquatic
snail Lymnaea stagnalis produced both penta- and heptapeptide
phytochelatins (i.e. phytochelatin-2 and phytochelatin-3), and their
levels increased in response to sub-lethal levels of cadmium.