Cloning without bacteria? Invitrogen offers kits for topoisomerase-based, directional, "vector-free" cloning. (Tools & Technology).(Brief Article)

Invitrogen Corp. of Carlsbad, Calif., offers TOPO[R] Tools for those interested in an alternative to conventional, time-consuming cloning techniques. TOPO Tools provide a relatively fast way of joining various sequence elements, such as promoters and tags, to either or both ends of a PCR-amplified product, without traditional cloning procedures such as ligations, vector manipulations, or Escherichia coli transformation. Rather, this method harnesses the dual catalytic activities of Vaccinia topoisomerase I: Sequence-specific cleavage and nucleic acid joining.

The researcher first PCR-amplifies the gene or gene segment of interest using a proofreading polymerase and …