Figure 1.

Strategy of RNA Recombination Experiments

(A) Scheme of recombination between nonreplicable fragments of an RQ RNA leading to generation of a replicable RNA.

(B) Sequences of foreign extensions (white letters on a black background) of the 5′ and 3′ fragments of the (−)-strand of RQ135⁻¹ RNA. A few base differences between the extensions (lowercase letters) serve as sequence markers. The fragment extensions consist of polylinker sequences providing for further manipulations of their structure at the DNA level.