of the F plasmid by acridine orange curing. Strains derived from MG1655 include DH1, parent of DH5α and in turn of DH10B (rebranded as TOP10 by Invitrogen). An alternative lineage from W1485 is that of W2637 (which contains an inversion rrnD-rrnE), which in turn resulted in W3110. Due to the lack of specific record-keeping, the "pedigree" of strains was not available and had to be inferred by consulting lab-book and records in order to set up the E. coli Genetic Stock Centre at Yale by Barbara Bachmann. The different strains have been derived through treating E. coli K-12 with agents such as nitrogen mustard, ultra-violet radiation, X-ray etc. An extensive list of Escherichia coli K-12 strain derivatives and their individual construction, genotypes, phenotypes, plasmids and phage information can be viewed at Ecoliwiki. B strain A second common laboratory strain is the B strain, whose history is less straightforward and the first naming of the strain as E. coli B was by Delbrück and Luria in 1942 in their study of bacteriophages T1 and T7. The original E. coli B strain, known then as Bacillus coli, originated from Félix d'Herelle from the Institut Pasteur in Paris around 1918 who studied bacteriophages, who claimed that it originated from Collection of the Institut Pasteur, but no strains of that period exist. The strain of d'Herelle was passed to Jules Bordet, Director of the Institut Pasteur du Brabant in Bruxelles and his student André Gratia. The former passed the strain to Ann Kuttner ("the Bact. coli obtained from Dr. Bordet") and in turn to Eugène Wollman (B. coli Bordet), whose son deposited it in 1963 (CIP 63.70) as "strain BAM" (B American), while André Gratia passed the strain to Martha Wollstein, a researcher at Rockefeller, who refers to the strain as "Brussels strain of Bacillus coli" in 1921, who in turn passed it to Jacques Bronfenbrenner (B. coli P.C.), who passed it to Delbrück and Luria. This strain gave rise to several other strains, such as REL606 and BL21. C strain E. coli C is morphologically distinct from other E. coli strains; it is more spherical in shape and has a distinct distribution of its nucleoid. W strain The W strain was isolated from the soil near Rutgers University by Selman Waksman. Role in biotechnology Because of its long history of laboratory culture and ease of manipulation, E. coli also plays an important role