Sub-lethal cadmium exposure increases phytochelatin concentrations in the aquatic snail Lymnaea stagnalis

Abstract

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. detoxification. In the present study, we show that the aquatic snail Lymnaea stagnalis 30 produced both penta-and heptapeptide phytochelatins (i.e. phytochelatin-2 and 31 phytochelatin-3), and their levels increased in response to sub-lethal levels of 32 cadmium. 33 34

Biomphalaria glabrata Metallothionein: Lacking Metal Specificity of the Protein and Missing Gene Upregulation Suggest Metal Sequestration by Exchange Instead of through Selective Binding

“…This was shown for Cd-exposed Physa acuta [ 9 ], metal-stressed Lymnaea stagnalis [ 20 ] or Cd-stressed Biomphalaria glabrata (this study). Instead, phytochelatin (PC) synthesis was recently demonstrated as a responsive reaction of Lymnaea stagnalis to Cd stress [ 8 ]. This suggests that apart from MTs, PC metal complexes may be formed in these aquatic snails in response to metal stress.…”

“…In freshwater pulmonate snails of the Hygrophila clade, the situation may be different. Although they possess MTs [ 7 ], an important pathway of metal detoxification in these species is represented by metal-binding to phytochelatins as shown, for example, for the Great Pond snail, Lymnaea stagnalis [ 8 ]. Accordingly, the capacity of Hygrophila to express MT s in response to metal stress is apparently inhibited or strongly reduced when compared to other gastropod species, as recently demonstrated in the Bladder snail, Physa acuta [ 9 ].…”

Challenging the Metallothionein (MT) Gene of Biomphalaria glabrata: Unexpected Response Patterns Due to Cadmium Exposure and Temperature Stress

“…This also suggests that MT may not necessarily be the main actor for Cd detoxification in Biomphalaria glabrata . Alternatively or concomitantly, phytochelatines may be involved in Cd detoxification, as shown for Cd-exposed Lymnaea stagnalis , a close relative of Biomphalaria glabrata [ 46 ]. Moreover, diurnal variability of physiological activity and age-dependent MT gene expression, as shown for MT genes of the land snails Cantareus aspersus and Helix pomatia , may also play a role [ 32 , 47 ].…”

“…It is assumed that the high constitutive expression of this MT may counteract metal stress by unspecific binding through metal exchange reactions at the protein’s binding sites [ 35 ]; in a similar way, the high constitutive expression level may also contribute to heat and cold shock tolerance. Alternatively, and/or concomitantly, Cd detoxification in Biomphalaria glabrata may also be achieved through complexation by phytochelatins [ 46 ].…”

Distinct pathways for zinc metabolism in the terrestrial slug Arion vulgaris

“…They can bind metal ions through the free thiols of their cysteine residues 33 . PCs are synthesized by phytochelatin synthase (PCS), an enzyme which has already been detected in several molluscan species 34 .…”