1. Center for the Biology of Nematode Parasitism, North Carolina State University, Raleigh, North Carolina 27695;
2. Department of Nematology, University of California, Davis, California 95616;
3. INRA, UMR 1301, F-06903 Sophia-Antipolis, France;
4. CNRS, UMR 6243, F-06903 Sophia-Antipolis, France;
5. UNSA, UMR 1301, F-06903 Sophia-Antipolis, France;
6. Divergence, Inc. St. Louis MO 63141 and Genome Center, Department of Genetics, Washington University School of Medicine, St. Louis MO 63108;,