Die Embryonalentwicklung der Paradiesschnecke ... - TOBIAS-lib

Kapitel 3: External and internal shell
formation in the ramshorn snail Marisa
cornuarietis are extremes in a continuum of
gradual variation in development 8
Leonie Marschner 1 , Julian Staniek 1 , Silke Schuster 1 , Rita Triebskorn 1,2 , Heinz-
R. Köhler 1
1 Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen,
D-72072 Tübingen, Germany
2 Transfer Center for Ecotoxicology and Ecophysiology, D-72108 Rottenburg, Germany
Abstract
Background: Toxic substances like heavy metals can inhibit and disrupt the
normal embryonic development of organisms. Exposure to platinum during
embryogenesis has been shown to lead to a “one fell swoop” internalization
of the shell in the ramshorn snail Marisa cornuarietis, an event which has
been discussed to be possibly indicative of processes in evolution which may
result in dramatic changes in body plans.
Results: Whereas at usual cultivation temperature, 26 ◦ C, platinum inhibits
the growth of both shell gland and mantle edge during embryogenesis
leading to an internalization of the mantle and, thus, also of the shell, higher
temperatures induce a re-start of the differential growth of the mantle edge
and the shell gland after a period of inactivity. Here, developing embryos
exhibit a broad spectrum of shell forms: in some individuals only the ven-
8 BMC Developmental Biology. 2013, 13:22
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