Cohen-Boyer-Berg experiment

From Genetics Wiki
Revision as of 20:50, 12 July 2014 by Floyd (Talk | contribs)

Jump to: navigation, search

In 1973 the first living genetically engineered transgenic organism was made in the Cohen-Boyer-Berg experiment.

A plasmid (pSC101[1]) containing a gene conferring resistance to tetracycline (Tcr) and an origin of replication was cut at a single site with the restriction enzyme EcoRI.

DNA from an African clawed frog (Xenopus laevis) was also cut with EcoRI and this yielded a range of DNA fragments including a large number of ribosomal DNA (that codes for rRNA) fragments[2] with matching "sticky ends".

Uncut-ecori-dna-and-plasmid.png

Cut-ecori-dna-and-plasmid.png

The cut plasmid and Xenopus DNA were mixed together with a ligase to repair the cut site, incorporating the Xenopus rRNA fragment into a fraction of the plasmids.

A population of E. coli cells were then transformed to incorporate the plasmids into their cells and grown on media containing tetracycline to select for the cells that contained the plasmid conferring tetracycline resistance. These could then be screened to identify the cells with plasmids that had incorporated the Xenopus DNA.

The end result was a bacteria that stably replicated a fragment of amphibian ribosomal DNA.

  1. ↑ The plasmid is named pSC101 because it was the 101st plasmid isolated by Stanley Cohen.
  2. ↑ Ribosomal DNA sequences are present in many copies in the genome and in Xenopus these contain two EcoRI sites close together.
Retrieved from "http://hawaiireedlab.com/gwiki/index.php?title=Cohen-Boyer-Berg_experiment&oldid=70"