Replication of a plasmid bearing a human Alu-family repeat in monkey COS-7 cells.

Monkey COS-7 cells were transformed with BLUR8 DNA, a pBR322 plasmid containing a human Alu-family sequence at the BamHI site. Within 24 hr of transformation 2-5% of the BLUR8 molecules recovered resisted cleavage by Dpn I, indicating they had replicated. Electron microscopy revealed appropriately sized circular molecules with replication bubbles whose centers were mapped to the Alu insert. A 16-base-pair deletion within the Alu sequence prevented replication. The results indicate that certain Alu sequences can serve as origins of replication in COS-7 cells.