1 We thank Erin Noonan, from the Tasmanian Department of Primary Industries and Water for providing platypus tissue samples. This work was supported by the National Science Fund for Distinguished Young Scholars (30725029), Program for New Century Excellent Talents in University of China (NCET-06-0117), the National Natural Science Foundation of China (30671497), the National Key Basic Research Program (NKBRP) (2006CB102100), the Swedish Research Council and the University of Sydney Research and Development Grant (to K.B.).
2 The IgD and IgO cDNA sequences reported in this study have been deposited in the National Center for Biotechnology Information GenBank under the accession numbers: EU503149-EU503150.
3 Y.Z. and H.C. contributed equally to this work.
4 Address correspondence and reprint requests to Yaofeng Zhao, State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, People’s Republic of China; Lennart Hammarstrom, Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska Instititet at Karolinska University Hospital Huddinge, Stockholm, Sweden; and Ning Li, State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, People’s Republic of China.
5 Abbreviations used in this paper: CH, heavy chain constant region domain; IGHC, immunoglobulin heavy chain constant region gene; PFGE, pulsed field gel electrophoresis; TM, transmembrane; BAC, bacterial artificial chromosome.
6 The online version of this article contains supplemental material.