Affiliation: | (1) Institut für Genetik der Universität zu Köln Weyertal 121, 5000 Koln-41, Germany;(2) Department of Biology, University of Essex, Wivenhoe Park, C04 3SQ Colchester, UK;(3) Present address: Biocentrum Basel, Department of Cell-biology, 4056 Basel, 70 Klingenbergstr, Seitzerland |