Nat. Biotechnol. 26, 259, 2008; published online March 2008; corrected after print 6 June 2008

In the version of this article initially published, in paragraph 7, beginning with line 2, the author incorrectly stated that “genes and promoters” were to be used; the line should have read “DNA sequences.” Also, beginning with line 6, author did not include the terms “with their natural promoters, terminators and introns,” between the words “species-specific genes” and “are transferred between.” Finally, also beginning on line 6, the author incorrectly used the terms “but use promoters from bacteria or other organisms.” The line should have read “using standard vectors based on foreign DNA.” The errors have been corrected for all versions of the article.