Project number		Stand-alone Projects  P24276
Title		Integrative developmental studies on basal molluscs
Principal investigator		WANNINGER Andreas
Approval date		03.10.2011
University / Research institution		Department für Integrative Zoologie, Universität Wien
Scientific field(s)
Keywords		neurogenesis, myogenesis, segmentation, molluscs, evolution, ontogeny
Homepage		http://zoology.univie.ac.at/people/staff/andreas-wanninger/

Molluscs exhibit a large variation of bodyplan morphologies that include millimetre-sized, worm-shaped, spicule-bearing "aplacophoran" groups (Solenogastres and Caudofoveata), eight-shelled polyplacophorans, bivalves, gastropods (snails and slugs), and cephalopods (nautiluses, squids, and octopuses). Despite recent technological progress in molecular and (micro-) morphological applications, the evolutionary emergence of the phylum Mollusca remains obscure. Questions whether or not molluscs are derived from a segmented ancestor (as the annelids) are still unresolved, and the discussion about their sister group is still ongoing. In order to shed light on these questions from a developmental perspective, we will investigate the ontogeny of nervous and muscle systems as well as the expression of "segmentation genes" in the Solenogastres, the recent group that is thought to bear most similarities with the last common ancestor to all molluscs. A recently established lab culture of four solenogaster species by one collaborator, Dr. Christiane Todt (University of Bergen), will provide us with the study material. Specific questions addressed include whether or not the expression patterns of the "segmentation genes" Notch, Delta, engrailed, wingless, and hedgehog bear any similarities to those of the segmented annelids and arthropods and/or what other functions these genes may have acquired during molluscan evolution. These studies will be performed on our model solenogaster species, Wirenia argentea. In addition, we will analyse neuro- and myogenesis in all four species with the aim to provide a model for the supposedly basal condition in Mollusca, and in order to test whether or not neural and/or muscular components in Solenogastres are formed in a strict anterior to posterior progression as in the segmented annelids. These data should provide us with in-depth insights into the basal neuromuscular and genetic toolkit of Mollusca and will allow us to propose an ancestral condition for these characters from which the other molluscan subtaxa derived. Moreover, the morphological data generated will provide potential insights into the phylogenetic relationships of Mollusca within Lophotrochozoa. In addition to that, the large EST dataset produced will provide an excellent data mining platform for future molecular analyses into the functions of numerous key developmental genes in basal molluscs, thus allowing for deductions concerning basal versus co-opted gene functions in the evolution of bodyplan novelties.