title: Turning snails into slugs: induced body plan changes and formation of an internal shell.
abstract: The archetypal body plan of conchiferan molluscs is characterized by an external calcareous shell, though internalization of shells has evolved independently in a number of molluscan clades, including gastropod families. In gastropods, the developmental process of torsion is regarded as a hallmark that is associated with a new anatomical configuration. This configuration is present in extant prosobranch gastropod species, which predominantly bear external shells. Here, we show that short-term exposure to platinum during development uncouples at least two of the processes associated with torsion of the freshwater snail Marisa cornuarietis. That is, the anus of the treated snails is located anteriorly, but the gill and the designated mantle tissue remains in a posterior location, thus preventing the formation of an external shell. In contrast to the prosobranchian archetype, platinum treatment results in the formation of a posterior gill and a cone-shaped internal shell, which persists across the lifetime. This first finding of artificially induced snail-slug conversion was also seen in the pulmonate snail Planorbarius corneus and demonstrates that selective alteration of embryonic key processes can result in fundamental changes of an existing body plan and-if altered regulation is inherited-may give rise to a new one.
authors.affiliation: Animal Physiological Ecology Department, Institute of Evolution and Ecology, University of Tübingen, D-72072 Tübingen, Germany.
authors.forename: Raphaela
authors.initials: R
authors.lastname: Osterauer
authors.forename: Leonie
authors.initials: L
authors.lastname: Marschner
authors.forename: Oliver
authors.initials: O
authors.lastname: Betz
authors.forename: Matthias
authors.initials: M
authors.lastname: Gerberding
authors.forename: Banthita
authors.initials: B
authors.lastname: Sawasdee
authors.forename: Peter
authors.initials: P
authors.lastname: Cloetens
authors.forename: Nadine
authors.initials: N
authors.lastname: Haus
authors.forename: Bernd
authors.initials: B
authors.lastname: Sures
authors.forename: Rita
authors.initials: R
authors.lastname: Triebskorn
authors.forename: Heinz-R
authors.initials: HR
authors.lastname: Köhler
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000187:drug effects*; D004625:Embryo, Nonmammalian / Q000187:drug effects* / Q000648:ultrastructure; D047108:Embryonic Development / Q000187:drug effects*; D004785:Environmental Pollutants / Q000633:toxicity*; D010984:Platinum / Q000633:toxicity*; D012908:Snails / Q000033:anatomy & histology / Q000187:drug effects* / Q000196:embryology
chemical_list: D004785:Environmental Pollutants; D010984:Platinum