Notes

+Present address: Fugro, Dillenburgsingel 69, 2263 HW Leidschendam, The Netherlands.

++Present address: EMBL, 6 rue Jules Horowitz, BP 181, 38042 Grenoble Cedex 9, France.

+++Present address: EMBL, 6 rue Jules Horowitz, BP 181, 38042 Grenoble Cedex 9, France.