Metals and metallothionein evolution in snails: a contribution to the concept of metal-specific functionality from an animal model group

Abstract

This is a critical review of what we know so far about the evolution of metallothioneins (MTs) in Gastropoda (snails, whelks, limpets and slugs), an important class of molluscs with over 90,000 known species. Particular attention will be paid to the evolution of snail MTs in relation to the role of some metallic trace elements (cadmium, zinc and copper) and their interaction with MTs, also compared to MTs from other animal phyla. The article also highlights the important distinction, yet close relationship, between the structural and metal-selective binding properties of gastropod MTs and their physiological functionality in the living organism. It appears that in the course of the evolution of Gastropoda, the trace metal cadmium (Cd) must have played an essential role in the development of Cd-selective MT variants. It is shown how the structures and Cd-selective binding properties in the basal gastropod clades have evolved by testing and optimizing different combinations of ancestral and novel MT domains, and how some of these domains have become established in modern and recent gastropod clades. In this context, the question of how adaptation to new habitats and lifestyles has affected the original MT traits in different gastropod lineages will also be addressed. The 3D structures and their metal binding preferences will be highlighted exemplarily in MTs of modern littorinid and helicid snails. Finally, the importance of the different metal requirements and pathways in snail tissues and cells for the shaping and functionality of the respective MT isoforms will be shown.

Global threat posed by metals and metalloids in the changing environment: a One Health approach to mechanisms of toxicity

“…Similarly, Dallinger (2024) discusses the environmental impact of some metallic trace elements (Cd, Zn, Cu) on the evolution of metallothioneins (MTs) in gastropoda, including snails, as well as their interaction with MTs. In particular, Cd has played an essential role in the development of Cd-selective MT variants but also adaptation to new habitats has affected the original MT traits in different gastropod lineages.…”

“…1). The impact of metals on microbial health provides insight into their mutual and symbiotic relationship (Ghio and Hilborn 2023;Ke et al 2023;Turner 2023) whereas metal detoxification and adaptive strategies in eukaryotes (Dallinger 2024;Putra et al 2023; Thévenod and Lee 2024) demonstrate important consequences of environmental and, in particular, soil health on plant and animal health. In mammalians, speciation of MMs determines their transport modality in the blood (Doroudian et al 2023) and distribution within cells, tissues and organs (Thévenod and Lee 2024).…”