If you are interested in a scientific walk down memory lane: tailed pBR322 Okayama, H. and Berg, P. Mol.Cell. Biol. 2:161 (1982). tailed pUC9 Heidecker, G. and Messing,J. Nuc. Acid Res. 11:4891 (1983). Regards from another Canuck. Karl the hepB guy