I am looking for a "blue" third chromosome balancer, i.e. one carrying a P-lacZ construct with easily identifiable Xgal staining pattern in the embryo. If you have one available, please let me know. Thanks very much in advance. Y. Henry Sun Inst. Mol. Biol. Academia Sinica Nankang Taipei 11529 Taiwan, ROC e-mail: mbyhsun at ccvax.sinica.edu.tw