TRANSFORMATION OF CA<sup>++</sup>-TREATED <i>recA</i> DERIVATIVE OF <i>ESCHERICHIA COLI</i> K12 BY λ<i>dv</i> DNA

Abstract

Plasmid Adv is an autonomously replicating circular DNA, which was derived from coliphage A, and which is perpetuated in E. coli cytoplasm This plasmid, consisting only of those genes and structures that act in the process of regulation and replication, can neither be wrapped in phage coat protein, nor conjugally transferred by itself between cells. The non-transmissibility, or "inertness" of this and several other similarly non-transferable plasmids (for a review, see Clowes 1972), has limited the studies on genetic organization of these genomes and on regulatory mechanisms acting in replication of the plasmids. Recently it was discovered that bacterial cellular surface is altered by treatment with Ca++ in such a way that the cells can uptake phage DNA (transf ection)