<figcaption> Credit: COURTESY OF TERRY SHARRER</figcaption>

In a series of experiments in the late 1960s and early 1970s, Stanley Cohen, Herbert Boyer, and their colleagues developed the techniques necessary to recombine genes in bacterial plasmids, allowing for their mass production and launching recombinant biotechnology as we know it.

In 1973, the Cohen-Boyer team introduced a plasmid fragment from one strain of Escherichia coli, conferring kanamycin resistance into another E. coli plasmid for tetracycline resistance, and then inserted the recombined DNA into live E. coli cells, which showed both characteristics.1 In 1974, they crossed species barriers, joining DNA fragments from Staphylococcus aureus, for ampicillin resistance, with the tetracycline resistance plasmid, and then cloned it into E. coli.2 Next they crossed kingdom barriers, inserting eukaryotic DNA - it was a ribosome gene from the African clawed frog, Xenopus laevis - into E. coli.3

The bacteria not...


1. S.N. Cohen et al., Proc Natl Acad Sci, 70:3240-4, 1973. 2. A.C. Chang, S.N. Cohen, Proc Natl Acad Sci, 71:1030-4, April 1974. 3. J.F. Morrow et al., Proc Natl Acad Sci, 71:1743-7, 1974.

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