The main research interests of our group are the reproductive physiology of polychaetes and the lipid transport in invertebrates. In all egg laying animals, supply of appropriate nutrients to the growing gametes is a prerequisite for the later development of the embryo. Oocytes import large amounts of micro- and macromolecules during oocyte growth.
The main storage product of oocytes are the female specific yolk proteins. Yolk proteins are imported in to the oocyte by receptor mediated endocytosis as the precursor, vitellogenin, which also transports some lipids. The rapid uptake of oocytes makes it a good model to study receptor mediated endocytosis. In polychaetes, vitellogenin is synthesized and released by specialized coelomic cells, the eleocytes. Once in the oocyte, vitellogenin is partially cleaved into its final storage form, vitellin and stored in small vesicles, the yolk granules or yolk platelets. In addition, other - sex unspecific - lipoproteins are also involved in the lipid supply to the oocyte but also to the growing male spermatogonia. These lipoproteins have initiated our interest in the structure and function of invertebrate lipoproteins in general. Our "model" organisms are the small polychaete Platynereis dumerilii, its larger relative Nereis virens and, more recently, crustaceans.